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Over the past several months, while researching different methods and systems for training, I’ve often landed on a home page explaining the ABCs of a given program. This would usually include a few action photos, a couple of catchy one liners, and some video examples: sprinting, jumping, lifting, and perhaps other standalone drills performed as part of a warm up or plyometric circuit.

Reading the comments and feedback from the consumers, I can tell that many of them are more enamored with the presentation and polarity of the program rather than the quality of the content. In other words, wrapping a philosophy up with a bow might make it look and sound great, but is it really doing what it claims? Additionally, does a philosophy holistically develop the athlete from the standpoints of speed, strength, agility, power, aerobic fitness, resilience, and technique? Or does it intentionally leave out certain aspects to pursue others ad nauseum? Are those aspects pursued at the potential risk of the athlete’s health and wellbeing? Are the right performance attributes being prioritized? How does each aspect in a given philosophy contribute or take away from performance?

These are a few of the questions in my mind when assessing any philosophy, whether in S&C, track and field, team sport development, academic study, or practical research—questions I don’t believe are thoroughly thought about nor addressed with enough intention.

Perfect Form for Lifts, but Not Sprints?

I currently run and operate a lone wolf, physical therapy clinic (one year) and athletic performance program (four years). When I am consuming information, working with physical therapy patients, or building programs, I often find myself switching and combining my roles and skillsets to help develop a more holistic picture of what is going on. Recently, most of the commotion on social media is generated around arbitrary outputs, whether it is lifting for max bar speed, max weight achieved, max sprint velocity, max effort, the list goes on.

In the presence of all of this max output, I find consistently that there’s rarely an emphasis on max technique, max finesse, max fitness, max resilience, or max strategic execution (outside of the weight room). Additionally, everyone is all about increasing speed reserve, but what about skill reserve? When I watch the videos, I am often in awe at how athletes at various levels can stay healthy while performing these exercises with blatant lapses in technique and posture, particularly in sprinting.

In the presence of all of this max output, I find consistently that there’s rarely an emphasis on max technique, max finesse, max fitness, max resilience, or max strategic execution. Share on X

I believe maximally performing sprints in this fashion creates ticking time bombs for various athletes in the form of injured hamstrings, shins, hip flexors, quads, feet, etc. Just as caution is demonstrated when overloading athletes in the weight room, I think it’s generally a good idea to allow technique to determine how often we push the limits in sprinting and other field-oriented activities (agility, deceleration, multi jumps, etc.) rather than forcing the output and hoping for the best.

This obsession with max outputs seems to have led many to forget that technique is often the limiting factor and that by solving the technical issue, the ceiling can be raised further in training density and in outputs. Ironing out the technical issues takes a skilled coaching eye and patience, as I’ve outlined in previous articles. In addition to identifying the technical flaw, the coach has to link it to injury risk so that they can make informed decisions with that athlete moving forward.

For example, when having an athlete squat in the weight room, most coaches would never have them put a bar on their back and ask them to max out if they have poor form. Why? Poor form shifts the concentration of stresses away from the desired muscles and towards more vulnerable muscles that aren’t ideal for bearing the brunt of the load in that given movement. Many coaches understand that this makes the athlete unnecessarily susceptible to injury and thus are typically on form patrol to ensure that doesn’t happen.

This obsession with max outputs seems to have led many to forget that technique is often the limiting factor, says @BrendanThompsn. Share on X

Acceptable form? Increase the weight. Sketchy form? Lower the weight. This concept is seemingly universally accepted and applied in the strength and conditioning community, most notably in the weight room. If the best ability is availability, why is sprinting treated differently?

Asking the Right Questions to Create Better Outcomes

When approaching training strictly from a performance standpoint, I often find myself watching and rewatching videos while looking for a set of qualities in the athlete or team, including:

• Intent
• Movement economy
• Subjective strain
• Other aspects of technique and execution

Along these lines, I start thinking about what I might change or reinforce. How might I cue them? What deficits do I see? What drills and other tasks might I give them to shift them to a better place on the mechanical spectrum?

These questions then begin to open up my physical therapy line of questioning. In the absence of a technical fix, what soft tissue structures are most likely vulnerable? What muscles are dominating this action and what tests might I perform to see if I’m right or wrong? Where are the major stresses occurring and why? Is there a reason for this compensatory pattern? What might my three biggest focuses be when building a preventative and corrective program for this athlete and why?

This is the type of internal dialogue I’m constantly having with myself to guide decision-making. It creates a cycle of using my physical therapy tools to help me design a performance program, while my performance tools often return the favor in helping me design a physical therapy program. Athletes are not simply performance machines where all that goes into performance is arbitrary output. Rather, they are a complex integration of psychology, biology, kinesiology, and other core sciences that make up the individual. Being complex organisms doesn’t mean that we have to expose the body to complex inputs, but rather simple inputs with strategic implementation that go well beyond being an arbitrary stimulus.

Athletes are not simply performance machines where all that goes into performance is arbitrary output. Share on X

Compare and Contrast: Sprinting vs Lifting

There is obviously a large difference between overloading a bar for a relatively unnatural movement sequence compared to maximally moving your own body weight in a rhythmic sprinting motion. A max squat and a max sprint only last a few seconds each, followed by substantial rest. Sprinting is a much more natural, (sometimes referred to as reflexive) motion than squatting and thus less likely to have the same magnitude of deficits as you may see in a squat.

Athletes have been running since their body allowed them to in early childhood development and the body has a way of self-organizing movement around its unique structure and function to get the task done. A coach can maximally sprint many in the general population without much risk, it just might not be fast. This is the side of the argument that says max sprinting is generally safer than max squatting, and I do agree that there is some validity to all of these points.

Let me paint a different picture, one that some may not consider when comparing the stimuli. Max weight room testing tends to be between 1 and 5 reps at a given weight (1RM, 3RM, 5RM,etc.), whereas a max sprint may be anywhere from 20-60+ reps (each foot strike is a maximal rep). In a typical sprint workout, you may accumulate that same amount of steps 4-10+ times. So overall, you’re accumulating 100s more maximal reps in repeated sprinting than in a max weight room test.

To take this a step further, a sound lifting program is maxing out 1-3 days per month at most. The majority of structured lifting occurs at submaximal loads, with max day being the reward for the athletes after a tough block of training. Maximal sprints are performed several times, sometimes 2 to 4 days per week. Over the course of the month, the athletes have performed anywhere from 8 to 16 days of maximal effort sprinting. This means the athlete has accumulated 1000s more maximal reps (remember each step is a max effort motion) worth of sprint work compared to maximal lifting.

Now we can consider velocity. The bar speed during max testing is likely <0.5m/s, whereas the center of mass may be moving between 7-11m/s during a maximal sprint. For perspective, that sprint velocity is at least 14-22x faster than the bar speed expressed during max testing. Additionally, each step of a sprint may create ground reaction forces up to 5x the athlete’s bodyweight. While a max lift may have similar ground reaction forces, the discrepancy of 1-5 reps compared to several sets of 20-60 reps (steps) for sprinting shows that the cumulative stresses the body endures with sprinting over a session will far exceed that of a typical max lifting session.

Each step of a sprint may create ground reaction forces up to 5x the athlete’s bodyweight, says @BrendanThompsn. Share on X

When thinking about overload and wear and tear, is the athlete more likely to sustain an injury pushing their body to the limit in weights during max week once every month or two, or during regularly programmed max effort sprints that they do all the time? How does technique amplify or minimize this?

This isn’t to say don’t sprint or that either exercise is superior to one another; it is more to conceptualize that max sprinting potentially induces far more stresses to the body than max lifting and that if coaches are wary of max lifting when someone has bad form, they should be equally or more cautious with max sprinting someone with hazardous technique too frequently.

The Concept of Skill Reserve

As mentioned before, speed reserve is often pursued endlessly along with a variety of other max outputs, sometimes at the expense of the skill that goes into those outputs. Speed reserve is the idea that the faster an athlete is at max output, the faster that athlete will be when operating in a submax capacity or under fatigue. It will be easier for them to achieve, carry, and repeat higher submaximal speeds than their slower counterparts.

Now I’ll spin this into a related concept that we will call skill reserve, efficiency reserve, technical reserve, etc. The more skilled, efficient, or technical somebody is when operating at max capacity, the more skilled, efficient, or technical they will be when operating in a submax capacity and under fatigue. This concept can be applied in a multitude of ways across sports, work, life, and other tasks.

Every sprint is an opportunity to build efficiency, coordination, power, relaxation, finesse, rhythm, and more. This is what makes sprinting potent. It is not the simple fact that the outputs produced are difficult to match anywhere else; more so, it is the combination of attributes and energy systems working together in synchrony that stress the body in a variety of ways that very few exercises can (if any).

Every sprint is an opportunity to build efficiency, coordination, power, relaxation, finesse, rhythm, and more. Share on X

As a workout wears on, the body must also learn how to operate under fatigue to maintain a level of proficiency to complete the task. If a fresh athlete has poor mechanics and an associated higher mechanical susceptibility to injury, that same athlete—when operating under fatigue—will multiply that risk by some factor as their mechanics exponentially deteriorate with each additional rep.

The body actively copes with the stresses induced on it during a workout and will compensate accordingly. If the task at hand is to get from A to B as fast as possible and the body is nearing a breaking point, it will sacrifice coordination and rhythm in the name of speed to achieve this goal. To see this in action, look no further than the final 100m of the 400m dash or 400m hurdles; watch the last 200m of the 800m or the final lap of the mile. The athletes that break down the most also tend to decelerate the most, oftentimes costing them a spot in the final or a medal on the podium.

In the context of team sports, as fatigue sets in with an athlete, watch how sloppy their quality of play becomes. Uncharacteristic turnovers, bad throws, poor shooting, giving up plays they typically wouldn’t—the more flawed a given skill is when fresh, the more that skill will deteriorate under fatigue.

In contrast, the most skilled athletes when fresh will still be operating at a technical level head and shoulders above their opponents and peers when working under fatigue. Watch a local high school conference championship and compare the 8^th place runner with the first place runner in how they look when battling throughout the race. Next, compare that experience to watching Olympians battle it out where the skill discrepancy is far less than at the high school level.

There’s a certain grace to elite performance that is often overshadowed by their brilliant performances and otherworldly outputs. Unless an athlete is at a certain standard of excellence already, it is extremely difficult to work on the skilled aspects of performance when operating in top gear all the time. It takes skill to demonstrate grace while operating at maximal outputs, and ultimately this balance is what leads many to expressing their optimal performance when it matters: competition.

There’s a certain grace to elite performance that is often overshadowed by their brilliant performances and otherworldly outputs, says @BrendanThompsn. Share on X

To add to the concept of skill reserve, it is helpful to revisit the idea of how fatigue impacts performance. While two athletes may have identical skill levels, the athlete who is more resilient to that fatigue will ultimately express that skill competency much longer than the athlete who is susceptible to fatigue and breakdown. Additionally, when comparing two athletes, an athlete with greater skill may outperform an athlete with lesser skill for a period of time.

But if the more skilled athlete has a susceptibility to fatigue that the athlete with lesser skill doesn’t, the skilled athlete may eventually perform worse than the less skilled athlete as a game or competition wears on. This is why it’s generally good to train holistically, as it addresses every aspect of the game rather than a select few attributes that may only last for a short period of time.

Applying Skill Reserve to a Training Program

To bring things full circle now and apply this concept to sprinting, it’s helpful to revisit the weight room equivalent. When developing form, technique, and precision for someone in the weight room, is it best to practice with max or submax loads? In other words, is the athlete operating near their max when working on technique, or with a weight that is manageable that they feel they have good control over?

The answer here is simple: the manageable weight. As the athlete demonstrates mastery at said weight, they’re allowed to graduate to the next weight to continue challenging their body under harsher conditions. Once they’ve demonstrated a level of competency that seems to prove to you that their form will only falter when they’ve encountered a weight that is too heavy, it becomes easier for a coach to allow them to test the waters of where their current ceiling may be because it is not as big of a perceived risk as it was before.

Applying this type of progression to sprinting is difficult. Athletes demonstrate different mechanics at submaximal and maximal speeds that don’t seem to mirror each other as much as might be preferred. An athlete may look like they’re jogging during tempo and like they’re fighting for their life when going all out. With sprinting, I tend to take a reverse approach to the weight room squatting example. Rather than starting them off jogging and whatever else, I want to get an idea of what they look like when they sprint first and go from there. Does it appear forced? Rushed? Weak? Exaggerated? Awkward? Hazardous?

Athletes demonstrate different mechanics at submaximal and maximal speeds that don’t seem to mirror each other as much as might be preferred. Share on X

After a quick video assessment, I’m able to see what their immediate needs are and correct them with cues. The athlete then takes these cues and does another max sprint (or several). If they appear to be struggling with the changes at max effort, it is time for submax reps for practice. Take the timer away, take the arbitrary distances away, and let them experiment with the cues where they feel most comfortable and have a sense of control.

Repetition for these athletes will be their best friend in making meaningful changes. As a coach, it is important to problem-solve to find a way for the cues to click for them. This can be achieved by exposing the athletes to a wide variety of feedback, constructive drills, and positive reinforcement. Once an athlete has reached this point, I spend a large portion of time addressing these factors each session and then periodically letting them test the waters with what they’ve learned. I dial the sprinting back for the same reason we start athletes with lighter weights in the weight room: they need to be under control to make necessary adjustments.

I dial the sprinting back for the same reason we start athletes with lighter weights in the weight room: they need to be under control to make necessary adjustments, says @BrendanThompsn. Share on X

Patients that exhibit movement faults in my clinic don’t tend to respond well when the exercise is graded too high. Take, for example, a patient with a hip drop and the posterior gluteus medius not doing its job during the gait cycle. If I start them on a difficult exercise that exceeds their capacity for controlling the hip drop, the likelihood of that particular exercise improving the gait fault is slim to none.

So, it’s necessary to grade down to the nearest level where they demonstrate control, but still challenge them. As they demonstrate competency in the exercises or tasks I’ve given them, they can dip their toes in the water of more demanding tasks for better carryover and eventually conscious manipulation of the task I am trying to correct—in this case focused gait training with typical circumstances (variable surfaces, variable grades, distractions, stairs, differing speeds, etc.).

I look at sprinting and other training the same way. If I see faults at X-intensity that the athlete can’t consciously correct, the likelihood I can make meaningful mechanical changes at that intensity is low. Grading that level of sprinting down to a lesser intensity and searching for the sweet spot of controlled yet challenging will yield greater benefits to the athlete from a technical standpoint. In similar fashion, as they demonstrate some competency, it’s great to graduate the athlete to the next level or allow them to experiment with their new skills at max output to see if the carryover is there. If it is, awesome! If not, it’s my job to figure out why and what I can do about it.

Training is one big experiment with each athlete I encounter: finding what works for whom, when to implement it, and to what degree while continuing to assess strengths, weaknesses, and how I can continue to holistically build the athlete throughout.

Training is one big experiment with each athlete I encounter, says @BrendanThompsn. Share on X

Submax, Tempo, and Technical Mastery

I know up to this point it probably seems like I am against max sprinting but I most definitely am not. As a high level sprinter who has been exposed to long, slow training and short, fast training, I know there is a balance that must be struck to achieve optimal results. Too long and too slow builds the aerobic system more and won’t develop fast twitch fibers to the degree they need to reach the speed ceiling.

Conversely, too much short, fast training will yield a very explosive athlete who may not have the gas tank to repeat performance or even sustain a highly technical performance for a single repetition. Breakdown may happen prematurely, and as mentioned earlier, technique decay increases injury susceptibility, especially at maximal outputs.

Technique decay increases injury susceptibility, especially at maximal outputs, says @BrendanThompsn. Share on X

I am a big fan of maximal sprinting and a big fan of technical training, whether through tempo, drills, or submaximal sprinting. Many of you may be reading this and thinking submax sprinting and tempo are the same thing. By definition, submax just means anything under an all-out effort, so yes, tempo is technically submax sprinting—but I differentiate the two.

I look at submax sprinting as dialing the thermostat back from 100, to 99, 98, 97, etc. until I find the point at which the athlete can still run extremely fast while sustaining control. It looks and feels like a sprint, but without operating with the pedal to the metal. Conversely, tempo is a much slower, controlled, rhythmic type of run that helps the athlete learn how much effort they need to give to hit x pace, minimizing strain, and maximizing repetitions. Athletes that display control with tempo and submax sprinting tend to show some level of carryover in their skill mastery when resuming max sprinting.

The transitory period between submax technical improvements and testing the waters in max sprint carryover varies from athlete to athlete. Some athletes may catch on fast and be ready to implement relatively quickly, others may take more time before seeing meaningful changes made in that domain. Athletes will progress at their own pace, with a tendency for novice athletes to take a bit longer than those with a higher training age and maturity. Additionally, athletes that have gone through a significant growth spurt recently will have difficulty developing that coordination in a timely manner, as their body must reform connections to catch up with its recent changes.

Athletes will progress at their own pace, with a tendency for novice athletes to take a bit longer than those with a higher training age and maturity. Share on X

Technical changes that need immediate intervention tend to stand out in a bad way on video. A short list might include:

• Wild arm swing
• Excessive trunk rotation
• Lack of postural awareness
• Degree and progression of body lean
• Heel recovery
• Foot strike
• Hip and knee mechanics
• Head control

Some reasons for fixing these items include:

• Energy leakage
• Efficiency
• Power outputs
• Excessive stress to soft tissues
• Poor timing and sequencing
• Excessive braking
• Insufficient propulsion
• Other factors that may lead to suboptimal performance and injury

Excessive casting of the knee in a sprint places the hamstring in a lengthened position and typically the most vulnerable position. Now imagine an athlete does this habitually over 1000s of steps over a training period. This is where the ticking time bomb I referenced earlier tends to come into play in the form of a hamstring tweak, pull, tear, tendinopathy, tendonitis, etc. The injured athlete must then go to their primary care provider, athletic trainer, physical therapist, and/or other supporting staff to help remedy the situation through rehab, training modifications, and other means.

In the absence of a meaningful technical change, the athlete will go back to sprinting the same way they did before and the likelihood of another injury to the same tissue is greatly increased. The process is likely to repeat itself again and again. If you do what you’ve done, you get what you’ve got.

If you do what you’ve done, you get what you’ve got, says @BrendanThompsn. Share on X

This is one of many examples to illustrate the cumulative stresses of sprinting and the cost of poor technique. It’s not to say that sprinting is inherently dangerous and needs to be avoided, it is more so to say that in the absence of technical coaching, a sprinter with poor technique may underperform, increase their risk of injury, and subsequently, battling that injury over time will lead to chronically underperforming and further injuries.

My career progression is a great example of this as my high school peak was 10.98s 100m and 22.41s 200m my senior year, which wasn’t much better than what I ran as a freshman in high school (11.12s/22.83s). I trained, but I never understood there was strategy in racing, value in technique, or levels to performance. I just went for it every single day and only ever knew one gear: GO.

After entering college, I shaved time consistently each season, eventually achieving 10.57s/21.18s, a sub-21.0s time trial in practice, a 46.2s 400m split, and a 9.4s split on an All-American 4x100m that ran 39.12s at the NCAA Division I Outdoor Championships. With the help of coach Joey Woody, I was able to mature as an athlete and really understand how to apply the skill that allowed me to progress the way I did. This led me to eventually have the most healthy and prosperous season of my career.

I’m a sample size of n=1, but I’ve personally witnessed athletes all over the country follow similar progressions. Learning sprint technique was career defining for me and it took me really dedicating myself to learning the art of sprinting to finally have my moment in track and field.

Taking it to the Track

In summary, the current state of training is heavily focused around arbitrary max outputs, particularly in sprinting, without the appropriate technical focus needed to balance and hone those max outputs. I have found success in sprinting 2 to 3 days per week for advanced sprinters, but the largest improvements I’ve seen in performance have been through technical training and changing the speed demands of sessions to balance output with requisite posture and technique. Being willing to take the time to identify technical faults and iron them out has been one of the hardest, yet most fulfilling changes I’ve made to my program. It should not be beneath someone to slow things down to work on these alterations.

Lessening the loads in the weight room to refine technique and control is intuitive, and sprinting is no different. A submax sprint, tempo running, or other methods for instilling technique have been some of my most fruitful uses of time to complement the output aspect of training. Going 90-95%, while less physically demanding, is extremely demanding from a technical perspective. The cognitive demand during the task makes the submaximal efforts more demanding because it is working against the athlete’s natural tendencies, requiring total concentration throughout.

Taking the time to experiment with different cues, drills, and demonstrations to help my athletes understand what they’re doing and what is expected has helped them piece together better tendencies and many eventually have massive breakthroughs in their performances, all while staying healthier along the way.

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ACL injuries receive a tremendous amount of attention at all levels of sport, and for good reason. It is estimated that 250,000 ACL injuries occur annually in the United States, representing approximately $2 billion in medical and rehabilitation costs.¹ Many of these injuries occur in competitive athletes, with females demonstrating a particularly high risk for ACL injury in field- or court-based sports (e.g., soccer, lacrosse, basketball). The occurrence of a single ACL injury may result in many future complications, including reduced activity levels, cessation of sport participation, and a high risk for future ACL injuries.²

So, what do we currently know about ACL injury?

Without rehashing too much of a previous post on ACL mitigation strategies, most of the research and clinical practice has focused on biomechanical- and neuromuscular-based interventions. While these programs have been demonstrated to be successful³, the rates of ACL injuries are actually climbing in adolescents⁴ and remaining somewhat steady in professional athletes (figure 1).⁵

In this blog post, I share what we currently know about the sensorimotor contributions to ACL injury risk, as well as how we can utilize technology- and field-based training strategies to improve sensorimotor performance in our athletes.

*Author’s note: I define sensorimotor performance as the integration between perceptual sensory input (e.g., vision, hearing, touch) and biomechanical movement output (e.g., running, jumping, cutting, decelerating). There are varying definitions, but for the sake of clarity, this is my working definition for the remainder of the post.

A New View of ACL Injuries?

As you may know, many individuals—myself included—have devoted entire careers to understanding ACL injuries and strategies to mitigate this injury risk. My doctoral research examined the relationship between sports-related concussion and lower extremity/ACL injury risk in adolescent and collegiate athletes. With concussive injuries being classically defined by a temporarily altered sensorimotor state, I started to wonder how these attributes contributed to ACL injury (outside of athletes with a recent or past concussion history).

Previous research has identified biomechanical and neuromuscular contributors to ACL injury risk (dynamic knee valgus, quadriceps-to-hamstring strength ratio).⁶ However, this is not necessarily conclusive in all athlete populations.^7,8 While it is outside the scope of this article to discuss the extreme complexity of ACL injury, my current research has led me to believe that perhaps we are somewhat ignoring another important contributor to ACL injury…the brain!

My current research has led me to believe that perhaps we are somewhat ignoring another important contributor to ACL injury—the brain, says @JasonAvedesian. Share on X

Ultimately, the central nervous system (we can generally think of this as the brain and spinal cord) is the central driver of biomechanical and neuromuscular control. Before getting into the actual research, I want to take you along a theoretical approach to how the brain and sensorimotor performance may contribute to ACL injury.

Adding the Brain and Sensorimotor Performance to the ACL Injury Risk Equation

Let’s first give some thought to the actual complexity of a dynamic sporting environment. Take, for example, a collegiate midfield soccer athlete performing in a very intense match. Some of the key sensorimotor attributes to successful performance and staying injury-free may include:

1. Working memory and pattern recognition – Remembering and recognizing the opposition’s defensive scheme when in a certain position on the field.
2. Dual-tasking – Receiving the ball from their teammate while scanning the field.
3. Visual attention and multiple object tracking – Spatial recognition of the changing position of teammates and opponents.
4. Reaction time and processing speed – Avoiding oncoming defenders.

All of this must be completed within hundreds of milliseconds! When viewed from this perspective, we truly take for granted the complexity of sporting environments (and how athletes can make their performances in them look rather “effortless”). Any movement performed on the field requires a complex interaction between the environment and athlete (we can think of this as sensorimotor integration).

Basically, any interaction an athlete makes with their environment is based upon three general concepts: the nature of the information, the complexity of the action to be performed, and the number of available response options (figure 2). Regardless of the task, movement behavior is a constantly evolving process constrained by time, space, and decisions (figure 2).

What Does the Current Research Tell Us?

Much like examining movement biomechanics and muscular activity patterns, what if we could determine how an athlete’s central nervous system is performing? Luckily, researchers have initiated these studies in the hopes of quantifying sensorimotor performance as it relates to ACL injury risk. In this section, I will highlight some studies that have been conducted, along with areas for future research and sports science directions.

One of the first studies on the relationship between sensorimotor performance and ACL injury risk was conducted by Swanik and colleagues all the way back in 2007.⁹ In this study, the researchers collected preseason performance on a common concussion assessment (ImPACT) and then longitudinally tracked non-contact ACL injuries in a group of collegiate athletes. Compared to athletes of the same sport and position, athletes who sustained an in-season, non-contact ACL injury performed worse on all measures of the assessments, including reaction time, processing speed, and working memory.⁹

Follow-up studies in collegiate football athletes have demonstrated an association between worse visuo-motor reaction time and greater risk for non-contact lower extremity injury.^10,11 A recent investigation from one of my colleagues (Dr. April McPherson of the USOPC) determined that individuals post-concussion are at a 1.6x greater odds for an ACL injury compared to those without a concussive injury history.¹² Hot off the press last month, researchers determined that female lacrosse athletes are at a fivefold increased risk for ACL injury up to one year post-concussion.¹³

Compared to more established biomechanical & neuromuscular data, quantifying the influence of sensorimotor performance on ACL injury risk is relatively lacking and still very much in its infancy. Share on X

Compared to more established biomechanical and neuromuscular data, quantifying the influence of sensorimotor performance on ACL injury risk is relatively lacking and still very much in its infancy. From what we do know so far, however, there are three brain areas that may be most influential to sensorimotor performance and, in turn, risk for ACL injury.

1. Prefrontal cortex – Responsible for many roles, including information processing/filtering, executive function, and working memory performance.
2. Thalamus – Acts as a relay of motor and sensory signals to the cerebral cortex for higher-level processing.
3. Lingual gyrus – Responsible for visual perception and recognition of complex vision information.

My overall conclusion of the sensorimotor research to date is that athletes with relative deficits in sensorimotor performance may be more susceptible to ACL and lower extremity injuries during conditions of increased arousal (i.e., a sporting environment). While certainly more research is required (and there’s a lot of exciting work coming down the pipeline), we can at least begin to ask: how can we train the sensorimotor system?

Athletes with relative deficits in sensorimotor performance may be more susceptible to ACL and lower extremity injuries during conditions of increased arousal (i.e., a sporting environment. Share on X

Training the Sensorimotor System – Technological Advancements

Over the last decade, there have been some major advancements in “train the brain” technology. Devices and software such as sensory boards, reactionary light devices, stroboscopic eyewear, and virtual/augmented reality* attempt to target various sensorimotor performance attributes: visual spatial-attention and reaction time, working memory, pattern recognition, and multiple object tracking (figure 5). 

*Disclaimer: This blog post is not intended to be an endorsement of any one product. I am just sharing my personal experiences with these devices, along with some research-grade evidence to support their potential utility.

Before we decide to invest in new technology, let’s consider a recent paper from Hadlow and colleagues¹⁴ on the framework for utilizing sensorimotor technology (figure 6).

Based on the Hadlow model, there are three considerations when implementing new technology to train the sensorimotor system.

1. Targeted Perceptual Function – The ability to discriminate between athletes of various skill levels (e.g., professional athletes should perform better than adolescent athletes).
2. Stimulus Correspondence – Sensorimotor skill improvement should improve through targeted training (e.g., visual-spatial attention and processing speed should improve with stroboscopic eyewear training).
3. Response Correspondence – Trained sensorimotor skills should translate to enhanced on-field performance and reduced injury risk.

Of these three factors, response correspondence is the least studied in the sports science literature. However, it offers plenty of opportunities for researchers and sports scientists to explore how current sensorimotor technology/training strategies influence performance and injury risk. In the next sections, I will take a deeper dive into a few of these sensorimotor technologies.

Sensory Board Technologies

Sensory board training devices have become a popular tool for assessing and training a variety of sensorimotor abilities. From a sports science standpoint, here are a few considerations to collect the most accurate data from these devices:

1. Standardize the time of assessment – Sensorimotor performance can be affected by many internal and external stressors, including sleep quality¹⁵, anxiety levels¹⁶, fatigue¹⁷, and prior injury¹⁸. Therefore, longitudinal sensorimotor measures should be collected at the same time of day to minimize these effects. For example, it would not be ideal to collect a baseline preseason assessment at 6 a.m. and compare that to future assessments collected in the mid-afternoon during the season.
2. Standardize board height and distance – Most existing sensory board technology is based upon upper extremity sensorimotor performance. During each assessment, athletes should be placed at standardized locations relative to their height and arm length to ensure accurate comparisons across time. This standardization will be helpful in minimizing effects on central and peripheral visual reaction time.
3. Standardize attentional focus – This is the toughest standardization to implement without actual eye tracking technology. Devices such as Dynavision and Senaptec Sensory Station offer central fixation targets during certain sensorimotor assessments. It is important to instruct athletes to fixate on these targets, especially if the sports scientist or researcher is interested in collecting peripheral visual-spatial performance.

While sensory boards are a bit more costly than other sensorimotor technology, these devices can assess and train many important attributes such as eye-hand and eye-foot coordination, central and peripheral visual-spatial attention, multiple object tracking, working memory, and reaction time. Research indicates that worse performance on sensory boards is associated with greater risk for lower extremity injury in collegiate football athletes.¹⁹ Even if we do not have access to sensory board technologies, there are other options for assessing and training sensorimotor abilities.

Stroboscopic Eyewear

Stroboscopic technology within elite sport has been around for quite some time (check out this article dating back to MJ in his prime). Nowadays, the technology is very easy to use and implement within a sport and clinical setting (figure 7). The goal is to limit visual information by alternating between clear and opaque visual states while performing sport-specific activities. This technology may be particularly helpful for athletes who are over-reliant on vision (often the case in athletes during rehabilitation from lower extremity injury such as ACL²⁰) by re-weighting sensory input to vestibular and somatosensory systems during dynamic postural control tasks.²⁰

There are several sensorimotor abilities that may be trained when using stroboscopic eyewear, including external attentional focus, visual-motor processing speed for enhanced visual efficiency, working memory, anticipatory trajectory estimation (e.g., ball flight, oncoming opponent), and transient visual attention.^21,22 While this technology certainly requires more research and data, it appears that beneficial training effects may be seen in as little as three weeks.²³

Virtual Reality

Sports-specific virtual reality (VR) is another up-and-coming technology that will begin to permeate through training environments. In one of my previous stops at the Emory Sports Performance and Research Center (in partnership with Cincinnati Children’s Hospital), the research team developed sports-specific scenarios integrated within biomechanical analysis to better understand ACL injury risk during more realistic conditions.

The utilization of VR for sensorimotor training comes with many potential benefits for practitioners and clinicians:

1. VR offers fully immersive environments within clinical and/or laboratory settings for better replication of sports-specific demands.
2. Practitioners gain the ability to simultaneous collect neuromuscular and biomechanical outcomes related to ACL injury risk during VR assessments.
3. Similar to stroboscopic eyewear, utilizing VR may help an athlete transition from a predominately internal attentional focus to an external attentional focus during training.

Training the Sensorimotor System – Revisiting Technological Advancements

Overall, there are many emerging technologies that can be used to train the sensorimotor system. While the research and data still relatively lag clinical practice (spoiler: they usually do), there is certainly utility for all the previously discussed technologies. When revisiting the Hadlow framework¹⁴, it appears that stroboscopic eyewear and sports-specific VR may be the most effective devices for training, while sensory board technology may be best for standardized assessments and monitoring change over time (figure 8).

Stroboscopic eyewear & sports-specific VR may be the most effective devices for training, while sensory board technology may be best for standardized assessments and monitoring change over time. Share on X

To reiterate, much more sports science research is required on all these technologies, but I am confident that we will see much more of that over the next few years. My advice to clinicians and sports scientists looking to invest in sensorimotor technology: first determine how feasible it will be to implement within your athletes’ specific training environment. Once you decide that, you will be able to make the appropriate choice(s) that fit your needs.

While we all love technology and the great strides it has made for training our athletes, we must all consider more “field-based” training strategies. In this next section, I will discuss how we can capitalize on agility training to develop sensorimotor abilities.

Agility vs. Change of Direction

Before diving too deep, I must first briefly discuss the differences between agility and change of direction (COD) training. While both have merit within a training model, it is important to distinguish between the two to target desired outcomes. As defined by Sheppard and Young (2006)²⁴, agility is a rapid, whole-body movement in response to a stimulus, while COD is a rapid, whole-body movement that is pre-planned. Keep in mind, COD qualities are instrumental for agility performance. But when examining the two from a sensorimotor perspective, there are important differences:

• Agility attributes – Anticipation, visual-spatial attention, pattern recognition, visuo-motor processing speed, and reaction time.
• COD attributes – Technique, linear/horizontal speed, neuromuscular asymmetry, and eccentric and deceleration control.

The environment we place our athletes in may also be quite different when targeting agility versus COD attributes. Agility-based training is more random and chaotic (open-skill abilities), while COD training tends to be more controlled and pre-planned (closed-skill abilities). COD training is inherently stable, while agility situations present an unstable environment in which an athlete is under various demands/constraints from teammates and opponents, all while having to anticipate and make decisions under time and space constraints (see figure 2).

While all athletes can benefit from both styles of training, novice athletes or those in the early stages of injury rehabilitation should be initially placed in COD environments and then progressed to agility environments. The figure I created below provides a quick overview of the important aspects of agility and COD (figure 9).

Much like neuromuscular strength training, we can progress agility training to place greater sensorimotor demands on our athletes. Check out a previous blog post in which my colleague Corey Peterson (University of Minnesota) provides a great progression from COD training to agility training. There are near infinite possibilities with agility training.

Determine the sensorimotor demands placed on your athletes and mimic your training environment to better replicate those demands, says @JasonAvedesian. Share on X

The bottom line: determine the sensorimotor demands placed on your athletes and mimic your training environment to better replicate those demands.

Sensorimotor Considerations During Injury Rehab

Unfortunately, we will not be able to prevent all lower extremity/ACL injuries from occurring in sports. In the event of an ACL injury, we must be aware of the sensorimotor contributions during rehabilitation so that we can reduce the risk of future injury. As we know, ACL injury rehab can be very complex and may not follow precise timelines due to setbacks. In the sub-acute, acute, and even chronic stages of post-ACL injury, physiological responses such as pain, stiffness, and swelling may occur.^25,26 This may lead to ruminating-type behaviors and psychological distress appearing in the form of anxiety, fear of reinjury, and decreased confidence to return to previous performance levels.²⁷

We can think of this psychological response as simply stress that athletes must manage while returning from injury. High stress levels are associated with delayed reaction times²⁸, reduced attention capacity²⁹, and internal attentional focus³⁰, all of which can be thought of as sensorimotor deficits (figure 10).

Aside from restoring neuromuscular and biomechanical performance capacities, we must consider the restoration of psychological and sensorimotor abilities during ACL injury rehab. The previously mentioned technologies are fantastic tools for these exact purposes, especially early in the rehab progression when athletes may not be able to get full “physical reps.”

Besides restoring neuromuscular and biomechanical performance capacities, we must consider the restoration of psychological & sensorimotor abilities during ACL injury rehab, says @JasonAvedesian. Share on X

*Author’s note: If you are interested in the actual brain neurophysiological response to an ACL injury, I would highly recommend checking out the work of my colleague Dr. Dustin Grooms at Ohio University. He has done tremendous work in this space and has been greatly influential on my current understanding of the sensorimotor contributions to ACL injury.

Relationship Between Concussion and ACL Injury

Much of my personal motivation on sensorimotor contributions to ACL injury came from my PhD studies at UNLV and Michigan State University. My dissertation research focused on how sports-related concussion and neurocognition influenced lower extremity biomechanics and injury risk in adolescent and collegiate athletes.^31–34 Prior data has determined that athletes and military personnel are at approximately 2–3 times greater risk for lower extremity injury post-concussion (figure 11).^35–39

As mentioned earlier, recent research indicates a specific relationship between concussion and ACL injury risk.^12,13 Transient deficits in cognition and oculomotor performance are hallmark signs of a concussive injury, but researchers are beginning to think that more subtle sensorimotor deficits may still linger even after athletes have been cleared to return to sport. The previously discussed sensorimotor topics in this blog post can certainly apply (and perhaps be very effective) during the acute and chronic time periods post-concussion to mitigate future risk for lower extremity and ACL injuries.

Concluding Thoughts – Future Opportunities to Reduce the Risk of ACL Injury

While we know quite a bit about ACL injuries from biomechanical and neuromuscular perspectives, we still have much to discover in terms of how sensorimotor performance contributes to ACL injury risk. With the research and information I have gathered at this stage in my career, here is my proposed pathway to ACL injury (figure 12):

1. Cascading events that begin with decreased visual-spatial attention, delayed reaction time/processing speed, and/or reduced working memory.
2. Perception-action mismatch between the athlete and surrounding environment (e.g., mistimed estimation of a defender’s trajectory toward the athlete).
3. Delayed neuromuscular response (e.g., anticipatory quadriceps and hamstring response) that results in increased load on the knee joint during high-impact loading events.
4. Increased risk for ACL injury.

If you take one thing away from this entire blog post, I hope it is that we have a great opportunity to modify sensorimotor risk factors and incorporate sensorimotor training within previously established neuromuscular and biomechanical interventions to reduce the risk of ACL injury.

Header photo by Tony Quinn/Icon Sportswire.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

References

1. Bates NA, McPherson AL, Rao M, Myer GD, and Hewett TE. “Characteristics of inpatient anterior cruciate ligament reconstructions and concomitant injuries.” Knee Surgery, Sports Traumatology, Arthroscopy. 2016;24(9):2778-2786.

2. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, and Hewett TE. “Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport.” Clinical Journal of Sport Medicine. 2012;22(2):116-121. doi:10.1097/JSM.0b013e318246ef9e

3. Webster KE and Hewett TE. “Meta-analysis of meta-analyses of anterior cruciate ligament injury reduction training programs.” Journal of Orthopaedic Research. 2018;36(10):2696-2708. doi:10.1002/jor.24043

4. Beck NA, Lawrence JTR, Nordin JD, DeFor TA, and Tompkins M. “ACL tears in school-aged children and adolescents over 20 years.” Pediatrics. 2017;139(3). doi:10.1542/peds.2016-1877.

5. Injury Data Since 2015. NFL.com. Accessed August 7, 2021. https://www.nfl.com/playerhealthandsafety/health-and-wellness/injury-data/injury-data

6. Hewett TE, Myer GD, and Ford KR. “Anterior cruciate ligament injuries in female athletes: Part 1, mechanisms and risk factors.” American Journal of Sports Medicine. 2006;34(2):299-311. doi:10.1177/0363546505284183

7. Cronström A, Creaby MW, and Ageberg E. “Do knee abduction kinematics and kinetics predict future anterior cruciate ligament injury risk? A systematic review and meta-analysis of prospective studies.” BMC Musculoskeletal Disorders. 2020;21(1):563. doi:10.1186/s12891-020-03552-3

8. Krosshaug T, Steffen K, Kristianslund E, et al. “The Vertical Drop Jump Is a Poor Screening Test for ACL Injuries in Female Elite Soccer and Handball Players: A Prospective Cohort Study of 710 Athletes.” American Journal of Sports Medicine. 2016;44(4):874-883. doi:10.1177/0363546515625048

9. Swanik, Covassin T, Stearne DJ, and Schatz P. “The relationship between neurocognitive function and noncontact anterior cruciate ligament injuries.” American Journal of Sports Medicine. 2007;35(6):943-948.

10. Wilkerson GB. “Neurocognitive reaction time predicts lower extremity sprains and strains.” International Journal of Athletic Therapy and Training. 2012;17(6):4-9.

12. Wilkerson GB, Simpson KA, and Clark RA. “Assessment and training of visuomotor reaction time for football injury prevention.” Journal of Sport Rehabilitation. 2017;26(1):26-34.

13. McPherson AL, Shirley MB, Schilaty ND, Larson DR, and Hewett TE. “Effect of a Concussion on Anterior Cruciate Ligament Injury Risk in a General Population.” Sports Medicine. 2020; 50(6):1203-1210.

14. Lutz RH, DeMoss DJ, Roebuck EH, Mason T, and Eiler BA. “Sport-Specific Increased Risk of Anterior Cruciate Ligament Injury Following a Concussion in Collegiate Female Lacrosse.” Current Sports Medicine Reports. 2021;20(10):520-524. doi:10.1249/JSR.0000000000000839

15. Hadlow SM, Panchuk D, Mann DL, Portus MR, and Abernethy B. “Modified perceptual training in sport: A new classification framework.” Journal of Science and Medicine in Sport. 2018;21(9):950-958. doi:10.1016/j.jsams.2018.01.011

16. LaGoy AD, Ferrarelli F, Sinnott AM, Eagle SR, Johnson CD, and Connaboy C. “You Snooze, You Win? An Ecological Dynamics Framework Approach to Understanding the Relationships Between Sleep and Sensorimotor Performance in Sport.” Sleep Medicine Clinics. 2020;15(1):31-39. doi:10.1016/j.jsmc.2019.11.001

17. Nieuwenhuys A and Oudejans RRD. “Anxiety and perceptual-motor performance: toward an integrated model of concepts, mechanisms, and processes.” Psychological Research. 2012;76(6):747-759. doi:10.1007/s00426-011-0384-x

18. Pageaux B and Lepers R. “The effects of mental fatigue on sport-related performance.” Progress in Brain Research. 2018;240:291-315. doi:10.1016/bs.pbr.2018.10.004

19. Busch A, Blasimann A, Mayer F, and Baur H. “Alterations in sensorimotor function after ACL reconstruction during active joint position sense testing. A systematic review.” PLoS One. 2021;16(6):e0253503. doi:10.1371/journal.pone.0253503

20. Grooms D, Appelbaum G, and Onate J. “Neuroplasticity following anterior cruciate ligament injury: a framework for visual-motor training approaches in rehabilitation.” Journal of Orthopaedic & Sports Physical Therapy. 2015;45(5):381-393. doi:10.2519/jospt.2015.5549

21. Kim KM, Kim JS, Oh J, and Grooms DR. “Stroboscopic Vision as a Dynamic Sensory Reweighting Alternative to the Sensory Organization Test.” Journal of Sport Rehabilitation. 2020;30(1):166-172. doi:10.1123/jsr.2019-0466

22. Appelbaum L and Erickson G. “Sports vision training: A review of the state-of-the-art in digital training techniques.” International Review of Sport and Exercise Psychology. 2016;11:1-30. doi:10.1080/1750984X.2016.1266376

23. Appelbum LG, Cain MS, Schroeder JE, Darling EF, and Mitroff SR. “Stroboscopic visual training improves information encoding in short-term memory.” Attention, Perception, and Psychophysics. 2012;74(8):1681-1691. doi:10.3758/s13414-012-0344-6

24. Shekar SU, Erickson GB, Horn F, Hayes JR, and Cooper S. “Efficacy of a Digital Sports Vision Training Program for Improving Visual Abilities in Collegiate Baseball and Softball Athletes.” Optometry and Vision Science. 2021;98(7):815-826. doi:10.1097/OPX.0000000000001740

25. Sheppard JM and Young WB. “Agility literature review: classifications, training and testing.” Journal of Sports Science. 2006;24(9):919-932. doi:10.1080/02640410500457109

26. Filbay SR and Grindem H. “Evidence-based recommendations for the management of anterior cruciate ligament (ACL) rupture.” Best Practice & Research: Clinical Rheumatology. 2019;33(1):33-47. doi:10.1016/j.berh.2019.01.018

27. Wang B, Zhong JL, Xu XH, Shang J, Lin N, and Lu HD. “Incidence and risk factors in joint stiffness after Anterior Cruciate Ligament reconstruction.” Journal of Orthopaedic Surgery and Research. 2020;15(1):175. doi:10.1186/s13018-020-01694-7

28. Meierbachtol A, Obermeier M, Yungtum W, at al. “Injury-Related Fears During the Return-to-Sport Phase of ACL Reconstruction Rehabilitation.” Orthopaedic Journal of Sports Medicine. 2020;8(3):2325967120909385. doi:10.1177/2325967120909385

29. Tomczyk CP, Shaver G, and Hunt TN. “Does Anxiety Affect Neuropsychological Assessment in College Athletes?” Journal of Sport Rehabilitation. 2020;29(2):238-242. doi:10.1123/jsr.2018-0123

30. Oudejans RRD, Kuijpers W, Kooijman CC, and Bakker FC. “Thoughts and attention of athletes under pressure: skill-focus or performance worries?” Anxiety Stress Coping. 2011;24(1):59-73. doi:10.1080/10615806.2010.481331

31. Mullen R, Faull A, Jones ES, and Kingston K. “Attentional Focus and Performance Anxiety: Effects on Simulated Race-Driving Performance and Heart Rate Variability.” Frontiers in Psychology. 2012;3:426. doi:10.3389/fpsyg.2012.00426

32. Avedesian JM, Covassin T, Baez S, Nash J, Nagelhout E, and Dufek JS. “Relationship Between Cognitive Performance and Lower Extremity Biomechanics: Implications for Sports-Related Concussion.” Orthopaedic Journal of Sports Medicine. 2021;9(8): 23259671211032250. doi:10.1177/23259671211032246

33. Avedesian JM, Covassin T, and Dufek JS. “Landing biomechanics in adolescent athletes with and without a history of sports-related concussion.” Journal of Applied Biomechanics. 2020;(Jul 31):1-6. doi:PMID:32736349

34. Avedesian JM, Covassin T, and Dufek JS. “The influence of sport-related concussion on lower extremity injury risk: A review of current return-to-play practices and clinical implications.” International Journal of Exercise Science. 2020;13(3):873-889.

35. Avedesian JM, Forbes W, Covassin T, Dufek JS. “Influence of Cognitive Performance on Musculoskeletal Injury Risk: A Systematic Review.” American Journal of Sports Medicine. Published online March 19, 2021: 363546521998081. doi:10.1177/0363546521998081

36. Brooks MA, Peterson K, Biese K, Sanfilippo J, Heiderscheit BC, and Bell DR. “Concussion Increases Odds of Sustaining a Lower Extremity Musculoskeletal Injury After Return to Play Among Collegiate Athletes,” American Journal of Sports Medicine. 2016;44(3):742-747.

37. Fino PC, Becker LN, Fino NF, Griesemer B, Goforth M, and Brolinson PG. “Effects of Recent Concussion and Injury History on Instantaneous Relative Risk of Lower Extremity Injury in Division I College Athletes.” Clinical Journal of Sports Medicine. 2019;29(3):218-223.

38. Harada GK, Rugg CM, Arshi A, Vail J, and Hame SL. “Multiple Concussions Increase Odds and Rate of Lower Extremity Injury in National Collegiate Athletic Association Athletes After Return to Play.” American Journal of Sports Medicine. 2019;47(13):3256-3262.

39. Lynall RC, Mauntel TC, Pohlig RT, and al. “Lower Extremity Musculoskeletal Injury Risk After Concussion Recovery in High School Athletes.” Journal of Athletic Training. 2017;52(11):1028-1034. doi:10.4085/1062-6050-52.11.22

40. McPherson AL, Nagai T, Webster KE, and Hewett TE. “Musculoskeletal injury risk after sport-related concussion: A systematic review and meta-analysis.” American Journal of Sports Medicine.

There have been a number of articles on this site dedicated to all aspects of movement in sports, such as acceleration, max speed, and change of direction patterns. The skill of moving well in competition is not solely about doing each of these movement patterns in isolation—it’s about being able to transition from one movement pattern to another or to link patterns. I define good athletic movement as choosing the appropriate movement pattern at the appropriate time and executing it exactly as you want to. Athletes must not only be able to recognize and choose the correct movement pattern—which is a skill itself—but they also must be physically capable of fluidly transitioning from one movement pattern to another.

I define good athletic movement as choosing the appropriate movement pattern at the appropriate time and executing it exactly as you want to. Share on X

The movement patterns you see in athletics consist of a lateral shuffle, lateral run, hip turn, plyo step, and backpedal, curvilinear running, and linear running. In a previous article on multidirectional plyometrics, I covered these movements patterns and discussed examples of when you may see them in sport. It’s important that your athletes become proficient in each of these patterns, and depending on the sport and position, they may need to be exceptional in a few of these patterns.

Why Do We Need to Move Well?

Improving speed directly coincides with coordinating transitions between movement patterns with better timing and fluidity. Performing only agility drills—which are drills that involve a cognitive component—will not ensure quality movement transitioning between all patterns of movement. Frans Bosch explains this in his book Anatomy of Agility: “the information filter is determined not only by the quality of perception but also by the motor solutions that can be planned in the light of the information; so the filter also depends on the capabilities of the body.”¹ Once again, perception is only one part of the movement equation: if you do not have the physical capacity to coordinate between movement patterns, you are missing one of the most critical pieces of athletic development.

If you do not have the physical capacity to coordinate between movement patterns, you are missing one of the most critical pieces of athletic development. Share on X

Most sports do not involve movement from a static position. Therefore, being able to transition from one movement to another becomes even more critical. Here’s a quick example of just how often these types of transitions happen in sport:

A soccer defender performs a backpedal as an opposing wing approaches him. As the wing gets closer, the defender positions himself to direct that opponent toward the sideline. As the attacking player continues to approach with more speed, the defender performs a hip turn to transition from a backpedal to a lateral run. The attacker continues to pick up speed in an attempt to beat the defender wide and cut toward the goal. As this happens, the defender transitions from a lateral run to a curvilinear run. 

As you can see, in a simple game-like scenario, there are multiple transitions among movement patterns. Performing any of those linking patterns poorly could be the difference between allowing a scoring chance and making a stop. Going back to the example, what if the defender is not good at transitioning from a backpedal to a lateral run and this leads to a scoring opportunity? Was this caused by his perception or a lack of ability to fluidly link these movement patterns?

It’s this question that all coaches must answer—an athlete’s perception may tell them what to do, but they just may be poor at executing the transition.

Fluidly Linking Movement Patterns Together

I’ve referenced being able to fluidly transition from one movement pattern to another, but what exactly does that look like? When analyzing movement, you can get into extremely detailed discussions of joint angles and creating force through various positions, but for the purposes of this article, I’ll talk about some broad concepts of good movement. Most coaches can identify good movement when they see it, but unless you are looking at movement through video, it can be difficult to identify exactly what led to a poor transition from one pattern to another. The more video you watch of athletes of all skill levels and abilities, the easier it will be to pick up on some of the big differences.

Begin by looking at the movement in general. Does it appear to be somewhat robotic or are there smooth transitions between patterns? Robotic movement demonstrates a lack of coordination among joints. Some of the movement may be fluid, while other parts are not as smooth. It will look as if certain joints are frozen together.

After looking in general at the movement, begin looking at the foot and then work your way up the body. Look for a stiff plant from the foot upon any sort of repositioning or changing pattern. A stiff foot plant indicates more force directed into the ground. This is important because it helps maintain the stride frequency of the athlete. Athletes who move better from one pattern to the other are able to maintain their gait cycle compared to lesser-skilled movers. If less force goes into the ground when linking movement patterns, the frequency of an athlete’s gait will decrease, which means their overall speed is decreasing.

Continuing to work our way up the chain, we’ll take a look at what’s going on with the upper body. When performing any sort of directional change, the upper body should lead the movement. If an athlete is sprinting straight ahead and they make a cut to the side, the upper body should slightly turn that direction prior to the hips turning that direction. If it were the other way around—where the hips lead the movement—the upper body would lag behind, which makes that change of direction slower and less efficient.

It’s not uncommon to see an athlete perform transitions between certain patterns well and others not so well. You may also notice an athlete performing transitions well toward one direction compared to the other. I’ve specifically noticed this with defenders who play on one side of the field all the time. Often, a defender tries to take away the middle of the field and push the offensive player toward the sidelines. If a defender is playing the right side of the field, they are turning to their right far more often than their left. However, getting out of position and being forced to turn to their left can expose a poor linking skill.

Create a Theme for the Day

As strength coaches, most of us don’t have the ability to train our athletes for endless amounts of time. We may get one hour to train them. One hour is not enough time when you start to include a warm-up, plyometrics, speed training, and resistance training—you may only get about 15 minutes of actual speed training for the day. If that’s the case, you’ll be hard-pressed to expose your athlete to all patterns of movement without a well-thought-out plan.

Creating a theme for the day will give you a general focus as a coach and allow you to explore some other movement possibilities in terms of speed training. You may want your athletes to work on curvilinear running one session—instead of just having them run curves from a standard static start, you can begin to work on transitions by performing them prior to your curvilinear run. A hip turn, linear sprint, lateral run, and lateral shuffle can all be mixed in prior to running around a curve. While the focus may be on curvilinear running, you are still exposing your athletes to a variety of movement skills.

Try to find movement transitions that challenge the physical ability of the athlete. If every drill you do is easy, the athlete already has the physical capacity to perform the skill. Share on X

Try to find movement transitions that challenge the physical ability of the athlete. If every drill you do is easy, the athlete already has the physical capacity to perform that skill. Continuing to perform this skill will not expand their movement library. You can create more or less difficulty by manipulating the speed going into the transition as well as the angle coming out of the transition. Be sure to add variety into your training to enhance learning and build a bigger movement foundation.

Video 1. The transitions in this clip demonstrate how you can target one specific pattern—in this case a curvilinear run—while still incorporating a variety of other movement patterns. 

Multidirectional Plyometrics for Specific Movement Patterns

When I think about the greatest impact I can have on an athlete as far as transferring what I do in the gym out to the field, it’s improving the quality of linking skills and improving the speed and power at which the athlete performs transitions. These types of drills are great for teaching athletes to produce a high amount of force while limiting time on the ground.

Similar to choosing a theme for your speed training each day, you can perform multidirectional plyometrics to match a specific type of pattern you may be looking to improve. It may be improving power at an angle forward or backward or even directly to the side. Too often, we rely on only vertical or horizontal plyometrics, but as I discussed earlier, power on the field happens when transitioning between patterns—and that can happen at all angles and directions.

Video 2. The first part of the video shows a hip turn to a lateral run, followed by a sprint. Following this initial drill are a couple progressions to demonstrate how to develop more explosiveness when transitioning from the lateral run into the sprint.

Wrap-Up

As a coach, when you really start to look at how we can impact performance, it starts with improving the speed, power, and coordination ability of our athletes on the field. Moving well is a skill. Some athletes naturally have it, while others need to be taught.

Regardless of the level of experience of the athlete, continue to improve their physical capacity to move well, in addition to challenging and expanding their movement library.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

Reference

1. Bosch, F. Anatomy of Agility: Movement Analysis in Sport. 20/10 Publishers. 2020.

A few years back, I began working with an athlete who was coming off a very serious and rare form of thoracic cancer. For the sake of this article, we’ll call him Jake. He underwent multiple major surgeries over several years that required doctors to cut through his pec muscles, serratus anterior, lat, and about 40% of his upper abdomen; all of these surgeries were on the right side of his body. Due to the location of his tumors, they also had to break his sternum and several ribs to get to what they needed. His body was ravaged—a truly harrowing experience, to say the least.

Despite the hardships, Jake was fully committed to seeing his career through and was working his way back to being operationally fit for duty. I was extremely fortunate to be a small part of his return.

Debates on whether unilateral imbalances are detrimental, beneficial, or completely insignificant to sport have been fevered for years. And, in most cases, they have often been very siloed and shortsighted. The experience of working with profound cases, such as Jake’s, has helped me develop a broader perspective on the entirety of asymmetries. As such, in this article, I’d like to focus the discussion on the spectrum of asymmetrical imbalance and how it affects athletes/individuals spanning a variety of sport backgrounds.

Assessing Asymmetries

Rather than simply seeing asymmetries in sport as either good or bad, we need to appreciate the complexity and nuance. But the first priority is understanding that there are several variables to consider and numerous ways to discern the significance of unilateral imbalances. These factors are more or less significant depending on the athlete’s stage of development, the demands of their sport, and the position they play. A short list of the more prominent factors can be found in the graphic below.

Additionally, there are numerous ways to assess unilateral imbalances; again, with the testing priority and significance being determined on an individual basis. A few of my unilateral baseline assessments typically include left/right muscle girth (muscle atrophy), functional unilateral movements such as a loaded skater squat (strength), and a Y-balance test (stability/mobility). These are reasonably simple tests with high degrees of reliability that allow you to observe the margin of difference between sides with your athletes.

Few coaches would argue that comprehensive unilateral testing is a logical part of an athlete’s training process; however, the heated question remains whether these margins of difference should or shouldn’t be addressed or “corrected” with our athletes. The unfortunate reality is this just isn’t a cut-and-dried situation, and rather than seeking empirical boundaries or ranges, unilateral deficits should be viewed individually and as a spectrum—or, as I see it, functional or nonfunctional.

Few coaches would argue that comprehensive unilateral testing is a logical part of an athlete’s training process, but they disagree on whether the margins of difference should be ‘corrected.’ Share on X

Functional vs. Nonfunctional Asymmetries

A subtlety to the military population is recognizing that a large portion of their work demands are unilaterally dominant (e.g., shooting stance, swimming stroke, vehicle position, kit/weapon positioning). Given the extreme volumes and intensities they are exposed to, not only do unilateral imbalances result, but damage and injury are all but inevitable. Thus, almost every athlete I work with has nonfunctional asymmetries, and a robust injury history.

By determining whether an athlete’s asymmetries are functional or nonfunctional, we can create a clear delineation that can help guide training priorities and programming selections. This does not indict the athlete in any way; as I see it, this is just an arbitrary way for coaches to have a better foundation for training prioritization and specificity. Functional imbalances do not need to be deliberately addressed, as they likely offer more benefit to sport performance than they do potential injury risk.

Nonfunctional imbalances, on the other hand, should be a top training priority, as egregious margins of difference between sides can become an impediment to performance and an injury vulnerability. The predominant factors outlined above, in conjunction with the amount of asymmetrical imbalance, will determine how much we should emphasize reducing the margins of difference in training.

We need to recognize that all asymmetries are not created equal. Speaking specifically for athletes—especially at higher levels—they need unilateral dominance. I see this as “protective tension,” whereby the demands of competition over the course of several years have driven unique, specialized differences in morphology or function that are optimal for their performance. Sticking with the baseball example, consider the throwing shoulder and contralateral hip of a pitcher. The throwing arm will have unique adaptations—hyperlaxity (elbow), increased rotator cuff thickness, lat extensibility, etc.—that are needed for them to perform at a high level.

We need to recognize that all asymmetries are not created equal. Speaking specifically for athletes—especially at higher levels—they need unilateral dominance, says @danmode_vhp. Share on X

I believe there are two priorities here:

1. Don’t disrupt the imbalances too much while in-season; let the player help determine what the best ratio of differences may be.
2. During the off-season, address these margins of difference to recalibrate equilibrium and avoid egregious discrepancies.

The goal will be to work the athletes back away from the outer (extreme) ranges, so they go into the following season with more room for regression throughout the year. Analyzing it this way, you see why simply saying “asymmetries don’t matter” or “asymmetries always matter” is shortsighted and incomplete.

Video 1. Dumbbell offset single leg RDL. Off-season training may be the best time to program exercises to address asymmetries.

Determining Significance

It all comes down to what coaches/practitioners deem to be a significant difference, given the constructs of their sport. Considering my tactical population doesn’t need much unilateral dominance for the sake of performance, I try to simplify this by observing four primary criteria:

1. Muscular strength.
2. Joint ROM.
3. Muscular girth.
4. Stability/motor control.

Within each of these, I’ve observed that ~20% unilateral difference is loosely indicative of impaired biomechanical function and injury vulnerability for what their job demands of them.

We can then identify asymmetries as mild, significant, or extreme.

• Mild asymmetries are functional imbalances that present no increased likelihood for performance decrement or injury risk. This speaks to most non-specialized athletes and most individuals; in this case, unilateral deficits do not need to be a training priority.
• Significant imbalances are those that meet the criteria outlined above but may or may not provide functional advantage. This speaks to specialized athletes (i.e., throwing/OH athletes, stick sports, and field event athletes). You will need to strategically place the management of the margin of deficit throughout your training calendar.
• Extreme deficits occur mostly through injury (return to play), chronic development, or traumatic situations such as Jake’s. With these athletes, closing the gap is the main priority.

One area of the unilateral debate that appears to be less contentious is return to play. Dr. Matt Jordan, a world-class coach renowned for his extensive research on the neuromuscular aspects of return to play, is someone I’ve learned a lot from on this subject. In one of his studies on ACL return to play, the research team suggested that greater than 20% differences in L/R force profiles following ACL reconstruction place the athlete at a greater risk for reinjury. This was determined using the equation provided below. It was also importantly noted that strength deficits in this instance aren’t only injured versus uninjured side, but also the injured leg post-injury compared to pre-injury.

In the case of return to play, I would advise strength coaches to be vigilant in testing/assessing unilateral deficits once they’ve finished formal physical therapy. Bear in mind that in most PT/rehab settings, the protocols are often localized and isolated in nature. Where the PT’s job is to restore independent function and localized strength, I see our side of the return to play spectrum as restoring strength in a global and integrated sort of way.

Strength coaches should be vigilant in testing/assessing unilateral deficits once an athlete finishes formal PT. Our side of return to play is restoring strength in a global and integrated way. Share on X

Using the post ACL rehab example here, the PT will improve things like knee flexion/extension ROM and strength, while we improve load tolerance on split squats and the ability to cut/change direction between the injured and uninjured leg.

Addressing Deficits

There are three specific ways I go about addressing unilateral deficits, which for the most part can correspond to the degree of significance as outlined above. These strategies are removing bilateral loading (mild asymmetries), using biased training parameters (significant/extreme), and offset loading, which can be used in a variety of ways across the spectrums of asymmetry.

1. Removing Bilateral Loading

Removing bilateral movements from programming effectively forces each side to work independently for itself. This can be a good way to exploit less obvious unilateral deficits and challenge the athlete to work on less familiar patterns. When used strategically, this can be a simple and effective strategy to keep the body honest unilaterally. One population that I feel this is particularly applicable with is Olympic weightlifters. Although the sport of Oly is largely bilateral in nature, there is a high volume of unilateral dominance that accumulates over time due to the mechanics of the split jerk.

Considering the jerk is always performed with the same leg coming forward, this can take a toll on the hips and low backs of Oly athletes. Another subtlety to consider with the split jerk is the disproportionate stress placed on the feet and ankles during the jerk actions. A disruption to the ankle/foot (e.g., chronic turf toe in the back leg, immobilizing the talus on front leg) can have a global impact and become a significant impediment to training.

2. Biasing Program Parameters

This is something reserved exclusively for athletes who’ve exhibited significant, nonfunctional asymmetries. The use of programming bias is a nuanced approach and something that can be undertaken in a variety of ways. But to keep this simple, the purpose of using biased programming is to stress the non-dominant side “X%” more in training.

Broadly speaking, I use increased volume (i.e., more sets—not reps—on the nondominant side) to address muscular atrophy in early phase programming. Then, in later phase programming, I use increased intensity (i.e., relative higher loads on nondominant side) to close the gap on strength/power deficits.

3. Offset Loading

Offset is a versatile training application with an array of benefits. I recently published an article describing the benefits of offset loading for a sport performance population, but, as it applies in this context, offset work can be beneficial for addressing unilateral imbalances. In a sense, offset loading provides a unique effect in that it emphasizes one side of the body but still demands output from both. Movements become more demanding on trunk stability and core musculature and, I’d argue, collectively demand more from muscle groups (increased motor unit recruitment).

In a sense, offset loading provides a unique effect in that it emphasizes one side of the body but still demands output from both, says @danmode_vhp. Share on X

When we have a substantial margin of difference between the left and right extremities, there are numerous trunk adaptations that must subsequently take place to accommodate this unilateral dominance. And a residual effect of this can become the amount of torsion experienced at the spine, as the athlete has recurring disproportionate stress at certain junctions or on the discs themselves. While this may be difficult to measure in the practical sense, it’s important to appreciate that margins of difference between deep core muscles and offset loading offer a very simple way to attack the deficits effectively.

Programming Considerations

Programming variables are collectively based on how significant the deficits are and in accordance with the demands of sport/specialized development. Functional asymmetries do not need to be stressed as a priority; however, I believe there is merit to utilizing some of these strategies irrespective of imbalances. When specifically addressing nonfunctional imbalances, however, we should address the margins of difference by modifying programming variables and exercise selection.

In the case of Jake, over time the nature of his injuries shifted the way he did everything—from his posture to his gait and everything in between, he now accommodated for his right-side deficits. During our initial assessment, Jake had a more than 20-degree difference between left and right hip extension (deficit on left leg), significant differences in hamstring strength (deficit on left leg), and ankle dorsiflexion (deficit on right ankle). So, in addition to the more obvious unilateral imbalances on the right side of his upper body, we were really attacking this from all angles.

When specifically addressing nonfunctional imbalances, we should address the margins of difference by modifying programming variables and exercise selection, says @danmode_vhp. Share on X

I’ve used biased programming in a handful of cases, and this was certainly a feature of Jake’s programming. We followed a protocol of progressively increasing volume discrepancy (2:1, 3:1, and 4:1) with concurrent decreases in load discrepancy across a six-week training split. The volume bias proved to be effective, as we reduced the difference in arm circumference from around 4 inches to around 2 inches between the right and left biceps. We also worked in a good bit of offset loading, which I felt was specifically beneficial for his general motor control and trunk stability. A full breakdown of our programming split can be found in the graphic below.

Video 2. Dumbbell offset incline press.

On a micro view, the main goal with our primary lifts was to find exercises we could apply heavy loads to and create a high CNS strain. For Jake, these mainly included hex bar deadlifts and push press variations. I like to “double down” on primary lifts, loading both conventionally and in an offset fashion (see 1A/2A below). The secondary focus was to challenge motor control and trunk stability. We accomplished this utilizing a number of offset variations—DB/KB uneven applications for presses, pulling, and hinge patterns as well as a lot of band offset movements: split squat, marching, and bridge variations. A full sample is shown below:

Jake was one of those athletes who will forever stick with me. Not just because our time together became a catalyst for how I perceive training methods, but more so due to the indelible impression his valor and determination made on me. In a relatively short time frame (six weeks), Jake saw tremendous progress, adding 11 pounds of muscle, dropping about 2% body fat, and showing significant improvements in strength and capacity. Although we didn’t completely resolve Jake’s unilateral deficits, arbitrarily I would say he went from ~50% margins to ~25% across the board. This enabled him to continue his career, have control over his future, and, most importantly, continue to be a husband and father…which is what matters most.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

By Matt McInnes Watson and Ash Buckman

Plyometrics are a powerful training method used by many athletes within speed and power sports. The effectiveness of the training can transform an athlete’s ability to utilize and produce force quickly, with greater precision and locomotive control. The development of plyometrics as a training tool and its link with sport-specific expression of movement has grown in recent years and led to an increased use of plyometric exercises. The variations of plyometric movements range from highly dynamic, intense movements in a linear fashion to a large array of extensive landings and takeoffs in multiple directions and planes.

Despite the growth of the training method, the testing of plyometrics has been limited to vertical, angular, momentum-based (on the spot, up and down) movements. This type of movement enables us to determine simple measurements of ground contact time (GCT) and jump height/flight time (JH/FT) to calculate metrics like the reactive strength index (RSI). Although this may be deemed an effective way to measure forms of reactive strength and plyometric potency, it does not have the capacity to measure influences of horizontal-based momentum.

Although RSI may be deemed an effective way to measure forms of reactive strength and plyometric potency, it does not have the capacity to measure the influences of horizontal-based momentum. Share on X

Measuring jump height and/or the incoming momentum of a movement that possesses more of a horizontal focus (e.g., bounding) is difficult using force plate, camera, and VBT technologies. The influences on landings—such as incoming descent angle and velocity—can often produce data that is difficult for coaches to understand and use as part of their movement assessments. The sport science and coaching community understands the specificity of more horizontally focused plyometrics and their link to sporting movement—therefore, the need for a new testing and monitoring metric is critical!

Outputs and Momentum

As previously mentioned, RSI is a widely credited testing metric for providing simple output data to assess an athlete’s reactive strength. That being said, the data that is recorded may be deemed symptomatic, showing the outcome of a movement. Yet understanding the reasoning behind outcome variables can be more important and can often provide greater clarity on the athlete’s performance. In plyometric movements with varying approaches, we can identify differences in outcome performance through comparison of the incoming momentum of the previous movement.

When it comes to truly understanding what is happening at a given moment within sport or training, we must analyze influencing factors to determine the reasoning of the outcome. This can follow a process similar to a physical therapist taking medical assessments, looking at what contributed to the injury, and linking this to the symptoms. If we’re being overly critical of the output measures, we are only getting half the story, and it can become difficult for coaches to truly understand how to further change and impact these output metrics and athlete performance.

So how can different incoming momentums change the outcomes of a takeoff?

We need to consider the loading pattern and what influences that loading pattern:

• Did the athlete fall vertically?
• Did the athlete fall horizontally?
• Was the incoming momentum affected by a greater entrance velocity?
• Is that landing affected by a higher velocity produced by an increase in negative foot speed?

When you consider these questions, you can start to understand how just considering output metrics in dynamic movement is half the story. Another important consideration when asking those four questions is: what are the output metrics telling us?

There are three potential outcomes:

1. The athlete is gaining momentum.
2. The athlete is losing momentum.
3. The athlete is maintaining momentum. (Although this may be deemed as important, the likelihood of exact momentum maintenance is very low, and each landing to takeoff varies slightly.)

If we bring these influencing factors together with the potential outcomes, we often see these typical occurrences:

• Too fast incoming momentum = losing momentum (often seen in the triple jump).
• Too long falling momentum = losing momentum (often seen with depth jumps).
• Smaller incoming momentum = gaining momentum (often seen in acceleration-based practices).

When looking back at the first two examples here where the athlete is likely to lose momentum, be it speed and/or jump distance, we as coaches must assess how these influencing factors that may negatively affect performance can eventually be used advantageously for the athlete.

We need to understand how to assess our athletes’ movements & use a new form of plyometric testing to help positively impact their output capacities when dealing w/greater incoming momentums. Share on X

The reasons for declines in momentum in these instances are that the athlete cannot handle the eccentric forces upon landing and/or the rate in which the eccentric portion of the landing is loaded. It’s therefore our mission as coaches to understand how we can assess our athletes’ movements and use a new form of plyometric testing to help positively impact their output capacities when dealing with greater incoming momentums. By just assessing output metrics, it becomes difficult to disseminate this data into our coaching and identify ways in which we can affect technique and task to improve performance.

Video 1. Bounding exercise with flight times and RSR calculated.

The Reactive Strength Ratio (RSR)

The RSR is a measurement of both the incoming and outgoing momentum of a plyometric landing and its influence on the ground contact.

When looking to calculate RSR, the FT before and after a landing should be measured while monitoring GCT. By accounting for both FTs, the incoming approach can be used to assess its influence on GCT, outgoing FT, and the performance outcome (RSI). Both FTs are individually divided by the GCT, giving two initial RSI scores. The outgoing RSI is then divided by the incoming RSI to give a ratio of 1 based on the impact of incoming versus outgoing capacities.

RSR = (Outgoing RSI)/(Incoming RSI)

Incoming RSI: Flight time – 0.35/0.17 GCT = 2.05

Outgoing RSI: Flight time – 0.37/0.17 GCT = 2.17

RSR: 2.17/2.05 = 1.059

Understanding the Ratio

When delving into the data, it’s important to understand the ratio and what it tells us. A perfect ratio of 1 relates back to the maintenance of momentum, which could be classed as a state of equilibrium. We can then base all other movements, whether they’re <1 or >1, and account for them having either lost momentum or gained momentum.

Ratios greater than 1 (>1) suggest that the incoming flight time is managed well upon eccentric loading for the athlete and they’re able to handle the force to propel themselves out of the takeoff, creating a larger outgoing flight time (increasing momentum).

Ratios lower than 1 (<1) suggest a greater incoming flight time (e.g., a high platform depth jump) that the athlete struggles to couple the energy of to create an equal or larger outgoing flight time (losing momentum).

Due to the previously mentioned difficulties of achieving a perfect ratio of 1, bandwidths are used to gain a greater perspective of the athlete’s ability to utilize or not utilize incoming momentum. The initial bandwidths are set within the 10 percentiles of the ratio of 1 to provide coaches and athletes with a guide to get the most out of plyometric adaptations.

The reasoning behind staying within the bandwidths of 0.90 to 1.10 is to ensure that athletes are training within elastic/plyometric zones, whether that’s overloading the athlete by spiking the eccentric GRF or looking to produce a higher output through the concentric takeoff portion of a movement. It’s important to understand that when we step too far outside these bandwidths there becomes a point of diminishing return. Saying that using just movements that possess a ratio of 1 is the way to train for plyometric adaptations would be foolish, and obvious forms of overload (especially through eccentric loading—ratio of 0.90) are critical for developing athletes.

But too often, coaches and athletes bang on the doors of plyometric overload and leave aside critical areas for developing the velocity side of landings. We must understand that high GRF must come with rapid GCTs in order for movements to be reactive, elastic, and, most importantly, efficient.

It must be noted too that the optimal ratio of 1 can be a sign of locomotive rhythm for the athlete in a given exercise. Rhythm can be the foundation of force-velocity acquisition, showing that an athlete’s competencies at a given movement in time are handled with efficient locomotive properties.

Using the Data to Guide the Coaching Process

The common practice of dividing plyometrics into intensive and extensive movements has given coaches a simplistic way to program dynamic training. The split is a similar reflection of maximal and submaximal categorization of movement, which also has implications when measuring RSR.

Intensive or maximal plyometrics will be most critical for monitoring RSR bandwidth. Often, the use of maximal intent for a given task shows the true colors of how the body reacts to maximal output stimuli. This may highlight weak links and disconnects of skills that result in biomechanical faults that inherently diminish the performance of said task or movement.

Analysis of the movement using the RSR could be a way of discovering asymmetrical discrepancies or a lack of eccentric loading control of the given movement, says @mcinneswatson. Share on X

Coaches can be left second-guessing or unaware that an athlete’s RSI score may be low due to an overwhelmingly low ratio of <0.90 (high eccentric loading). Equally, monitoring of RSR bandwidth can be used to detect if the eccentric loading is placing enough stress on the athletes, with regard to producing ratios >1. This also plays a critical role in monitoring fatigue and potential overuse or stress-based injuries.

Extensive or submaximal plyometrics have a fundamentally different emphasis and intent—loading or output are not always KPIs. Submaximal strategies are implemented for physiological and neuromuscular adaptive reasons, such as:

• Higher landing volume to accommodate tendon CSA growth/stiffness.
• Better timing and efficiency of the SSC.
• Heightened proprioceptive awareness.
• Overall mechanical landing improvement.

As with many submaximal or extensive strategies for training, rhythm becomes the foundation of movement. It is usually the case that submaximal effort can give way to conscious, relaxed states to then place further efforts on smooth locomotion. This is achieved through, ideally, an optimal RSR of 1, when athletes are able to utilize and produce force efficiently. If an athlete is struggling to maintain speed, fluidity, or rhythm during an extensive plyometric activity, then analysis of the movement using the RSR could be a way of discovering asymmetrical discrepancies or a lack of eccentric loading control of the given movement.

Videos 2 & 3. Extensive crossover bounds and extensive split exchange leaps.

Optimal locomotive performance often requires movement in the most intense manner but is also achieved in the smoothest and most efficient way. Often in sport, the fastest and best performers aren’t always producing the highest force but are using it effectively to accomplish the sporting skill best (whether that’s sprinting, pitching a ball, or outmaneuvering a defender).

Therefore, our utmost aim as coaches is to develop movers who execute specifically intense movements like sprinting or bounding for distance with an optimal RSR of 1.

Our utmost aim as coaches is to develop movers who execute specifically intense movements like sprinting or bounding for distance with an optimal RSR of 1, says @mcinneswatson. Share on X

Further Observations and a Sampler of Unilateral Landings

There are two options for unilateral plyometrics:

• Hopping (unipedal—moving on just one leg).
• Bounding (bipedal—alternating legs).

Although both are considered unilateral, they have some inherent differences when it comes to landing forces, mechanics, and neuromuscular stimulus. A consideration and finding from the RSR brings up the asymmetrical differences that may be observed during bounding.

All athletes will possess an asymmetrical balance between legs, with what may be considered a dominant and nondominant leg. Other descriptions may be a “strength leg” and “speed leg” that are based on takeoff preferences in jumping actions.

This difference brings up scenarios during bounding that may sway the use of maximal intent versions. For an athlete with a dominant left leg, when bounding for distance left to right, due to the left leg’s capacity, the flight time of the incoming right leg landing is likely to be high. This subsequently has a knock-on effect due to the nondominant right side then having to deal with the larger incoming flight that will inevitably spike a high eccentric ground reaction force. The right leg’s inferior capacities can potentially have a further effect when coupling energy from what may be deemed a supramaximal landing, which cannot produce an equal outgoing flight time (= RSR <1).

This continues to have a knock-on effect with the lack of influence it may bring when alternating back to the dominant left side as it receives what should be maximal—but is in fact a submaximal—loading of the next landing due to the nondominant leg’s incapacities to utilize and express force. This leads the dominant left to then proceed in having to recreate momentum again (= positive RSR >1).

The scenario can create a vicious cycle where both legs are not training within the zones a coach may wish for, especially if the intent is to work on maximal output. This might be the typical response we may want with plyometrics, by highly loading the eccentric phase, but when using unilateral bipedal movement (bounding), this may bring up some faulty patterns that could lead to potential asymmetrical landing injuries.

It must be noted, too, that a certain level of dominance will always be there for some athletes but must only be present at a minimal level. Negative influences that were previously discussed must be monitored through the ratio to help determine further if gait and loading mechanics are leading to overuse and/or potential injury.

Final Takeaways

The RSR can be a great tool for evaluating and monitoring a particular plyometric or dynamic movement in time. The ratio can provide athletes with a measurement of their capacity to deal with all landing and takeoff scenarios, no matter the trajectory of the incoming movement.

The reactive strength ratio can provide athletes with a measurement of their capacity to deal with all landing and takeoff scenarios, no matter the trajectory of the incoming movement. Share on X

What’s important about the ratio is that it does not replace RSI but becomes part of the story for movement assessments. Output RSI is always present when measuring RSR, so you still get a value to determine the output capacity of an athlete’s reactive strength. With both load tolerance measured in the ratio and dynamic output from RSI, we can now better understand the reactive abilities of our athletes.

Since you’re here…
…we have a small favor to ask. More people are reading SimpliFaster than ever, and each week we bring you compelling content from coaches, sport scientists, and physiotherapists who are devoted to building better athletes. Please take a moment to share the articles on social media, engage the authors with questions and comments below, and link to articles when appropriate if you have a blog or participate on forums of related topics. — SF

Ash Buckman is a performance coach based in the U.K. who has a master’s degree in sport science. He has worked within many high-performance environments across sports including basketball, track and field, and motorsport. His work includes strength and conditioning and soft tissue therapy, with a strong interest in the use of plyometrics in sports performance.

Anyone who has taken biomechanics courses in college and survived to tell the tale understands how the academic world looks at human movement. It’s taught that the body consists of a series of muscles, connective tissues, and bones: this is a system of levers and pulleys creating locomotion.

While crunching complicated equations, most of us begin to compartmentalize action based on the surrounding muscle groups. And why wouldn’t we? The entire strength and conditioning field revolves around strengthening particular muscle groups. We have machines for biceps and entire days dedicated to legs. The internet is full of gurus whose Instagram handles include the words knee, hamstring, glute, etc. Our field mocks bodybuilders for their training methodologies and then applies the same kind of muscle idolization in its training.

So, how did this happen? To answer that, travel with me back to 2016, when I finished my master’s thesis (see the abstract for “The Impact of Three Different Forms of Warm Up on Performance”).

From the Playing Field to Academia

Before I conducted my research, I spent the year coaching athletes in the strength and conditioning program at Midwestern State University in Wichita Falls, Texas. Having played football and powerlifted for my university, I already knew what it was like to do the training. Like any new coach and grad student, I ate up the new nuggets of knowledge I gained. The purpose of my thesis was to check how different forms of warm-ups could positively or negatively affect power performance. I looked at the differences between the impact of dynamic warm-ups, static stretches, and foam rolling on peak power and range of motion.

At this time, there was a great deal of debate about whether foam rollers were worth the energy for a sports program. Old-school coaches looked at it as a waste of time, stating that rolling on a piece of plastic was a horrible way to start a workout. On the opposite side of the spectrum, new age gurus claimed a simple piece of foam could break down scar tissue within the muscle. (Fun fact: it cannot). For more than a year, I had started every session with rolling out, and I believed it improved how well I moved during my workout. This made me want to investigate two things:

1. Does myofascial release (foam rolling) have any positive or negative impact on training and performance?
2. If there is a positive impact, how does it work?

To answer the first question simply—foam rolling did seem to affect peak power or improve range of motion. To answer the second question complexly—a lot happens when pressure is applied to muscle and its connective tissue.

So, like any good grad student, I began researching how foam rolling affects the body and why it impacts performance. After a few weeks down the rabbit hole, I looked at myofascial release therapy and its effect on fascia. At this point in my career, I had compartmentalized the body into more than 600 different muscle groups. If your quad hurts, you need to fix your quad. If your shoulder blade “pinches,” you need to fix the muscles around your shoulder blade. After all, muscles are the main character in this movie.

Apparently not. I learned that our bodies are covered in an intertwining organ that is full of sensory receptors that can affect everything. From “tightness” to how the body can transfer energy between limbs, myofascia played a huge role. I had spent years thinking of the body as this series of segmented levers. All school taught me about fascia was that it covers our muscles—that was about it. It was during my own research that I learned the positive effect of foam rolling comes partly from the pressure feedback within the myofascia. This creates a cascade of events that not only improve the range of motion, but also the power an athlete can produce.

My light bulb moment: If the function of fascia can improve from rolling out, then emphasizing it in training surely would enhance performance, says @endunamoo_sc. Share on X

I had never considered the impact of how fascia can aid (or impair) movement. LIGHT BULB.

If the function of fascia can improve from rolling out, then emphasizing it in training surely would enhance performance! This organ doesn’t stop and restart at each bone like muscles; rather, it covers EVERYTHING. This is why you can stretch or massage the glute and relieve shoulder blade tension. Or how you can have someone who is weight room weak produce massive amounts of power and speed on the field. Skinny pitchers and lanky basketball players can do things that no elite-level powerlifter could dream of. This “discovery” helped me realize two huge concepts:

1. Anytime an athlete trains, we should organize sessions, microcycles, and macrocycles around more than just traditional strength training.
2. What made me into a great powerlifter might have been the same thing that made me such an injury-prone and average football player.

So, the big question is: “how do we train fascia?” The truth is that almost everything you do in sports and the weight room will train your fascia. Now, if you stop reading at that line, you will miss out on the UGLY truth of fascia: How you train affects your fascia.

Fascia is an interesting organ because of its adaptability. It can act like a sail, catching and sharing power across the body using mechano and chemoreceptors littered throughout. Not only does it adapt to stress in the form of normal loading, but it also can adapt specifically to the velocity at which it loads.¹

Fascia is an interesting organ because of its adaptability…Not only does it adapt to stress in the form of normal loading, but it can also adapt specifically to the velocity at which it loads. Share on X

In other words, if you only move slow, you create slow fascia. If you move in one pattern, your fascia will create lines of efficiency in these directions. The inverse is true as well. And unlike muscle, which can have growth and neurological adaptations in only weeks, fascia takes months to change. This becomes a problem when we neglect higher velocity training for predominantly heavy weight-based workouts.

During the COVID-19 lockdowns of 2020, athletes across many sports (except for a few basketball players in Disneyland) found themselves trapped in their houses and apartments. Gyms were closed, and nobody knew if it was safe to interact with each other in public. We were a community of individuals doing our best to get by. This resulted in elite-level athletes performing bootcamp-style workouts in their living rooms. Unfortunately, this predicament lasted longer than six weeks for most people. They went from sprinting, jumping, and moving at high speeds many times a week to doing nothing at all for months in a row.

Finally, once competitive athletics resumed, sports like football gave their top performers only a few short weeks to get back to “game speed.” This was when we saw the largest number of soft tissue injuries ever in the NFL. Between hamstrings, Achilles, and ACLs, some of the league’s best athletes were out for the year.² Although there isn’t a single source of blame, low-velocity workouts done for months with only a short time allowed for correction seems to just scream that it’s one of the culprits.

This is where my personal history comes into play—I was a perfect soldier of a football player. If you asked me to run through a brick wall, I would. No questions asked. My high school coach told me that if I wanted to be a great at football, I needed to do power cleans and squats—so I did. In college, I was the strongest in my class, so I always lifted with the upperclassmen. I enjoyed that title, and my strength coaches praised me for my weight room abilities. I got strong, I improved my vertical, and I got decently fast—but I was always getting hurt.

I also struggled with certain athletic traits that I knew I should be better at. I could dunk from a standing position, but barely jumped higher with an approach. I was a great 10-yard sprinter but was inconsistent with 40-yard distances. What I (and many coaches today) failed to realize was that I had spent so much time focused on muscle-specific strength training that I had neglected the fascial side of human performance: the athletic side, if you will.

How to Train Fascia

Go to any AAU basketball tournament and you will see some of the most athletic movements performed by the most gangly of individuals. A combination of explosive dunks, extreme footwork, and powerful sprints are done by “weight room weak” individuals. This has to make the most seasoned strength coach pause in their tracks when building the best programs for their athletes. Break basketball down into its base components, and it’s just jumping, sprinting, decelerating, and throwing. Because of the nature of the sport, there are more than 60 jumps per game and dozens of speed changes.³

If that is all it takes to create astounding athletes, why don’t we do more of that in the weight room?

In NO WAY am I saying that we should neglect the many benefits of strength training in the weight room. The sad truth, though, is that many high school and college coaches have turned the weight room into powerlifting, Olympic lifting, and body building centric zones. I believe that strength is the foundation to performance enhancement, but it, in and of itself, does not create the most athletic of individuals. If you’ve ever seen Usain Bolt’s weight room training, it will haunt your nightmares.

The way Bolt trained in the weight room likely had nothing to do with his world-record success. So, let’s look past the barbells, bands, and squat racks to determine what we can do for our athletes to create positive fascial adaptations. Many coaches already incorporate these things, but as the “garnish” of their workouts. I argue that we should find ways to make these the steak and potatoes of the hour. Squats, presses, and pulls will still be integral in building great athletes, but we need more of these four qualities in each session:

1. Throw Things

Throwing medicine balls is not just a baseball player’s job anymore. The way that the body has to transfer force from the ankle to the knee, to the hips, to the spine, to the shoulder, to the arm, and out of the hand, maximizes the fascial “sail.” Our facility has anecdotally used medicine ball throws with our varsity football players before sprinting with great return. The better the body is at transferring energy throughout, the more it will be able to handle energy during athletic performance.

Video 1. Athletes play med ball volleyball to further build explosiveness at the tail end of a summer development program with Endunamoo Strength & Conditioning.

2. Jump, Sprint, Land

Jumping and sprinting are some of the most primal of movements when it comes to being human. Although these movements can be very force dominant, you cannot deny the velocity-explicit components. A max effort jump will utilize the entire body to produce force both vertically and horizontally.

The more in tune with fascial transfer an athlete is, the better they seem to perform things like continuous jumps. The strongest powerlifter is NOT the fastest sprinter for many reasons, but one of them is the inability to rapidly transfer force across the body. Sprint fast and sprint often to convert muscular strength into athletic strength. Sports play is full of rapid eccentrics, but if I walked into any random high school or college weight room, I would most likely see nothing but tempo-controlled lifts. Rapid eccentric movements seem to excite more eccentric overload and induce greater stretch shortening cycles.⁴ Exercises such as depth drops, depth jumps, and even “rapid eccentric” weight room exercises will benefit most athletes.

Video 2. Advanced phases of a box jump progression targeting improved ground contact times.

3. Train Across the Body

If you want to understand how fascia connects our body, just watch sports. We instinctively know to apply forces across the body from one foot to the opposite hand, says @endunamoo_sc. Share on X

If you want to understand how fascia connects our body, just watch sports. A pitcher plants with their left foot before throwing from their right hand. A sprinter simultaneously drives the opposite knee and hand while running. A basketball player leaps off their left foot while winding up their right hand for a dunk. We instinctively know to apply forces across the body from one foot to the opposite hand.

Adding in training that works across the body can build these already natural fascial pathways. Things like landmine movements with rotation, single limb dynamic movements, and even trunk rotating exercises should be added at the appropriate times and intensities.

Video 3. Baseball players working cross chops and suspension rows to target the trunk muscles responsible for rotation/counter-rotation and scapular control. 

4. Train Along Lines

I am still surprised at how little people know about fascial lines. Granted, I researched fascia in grad school and had no clue this concept even existed. Many of the best coaches in today’s industry have concurred that the body contains “lines” that we can train to maximize. I’ve mentioned different exercises above that work across the body, but we cannot neglect these lines:

• Front line.
• Superficial back line.
• Lateral line.
• Spiral line.
• Back functional line.
• Front functional line.

Adding Intent to Common Practice

This sounds so simple, and most experienced strength coaches will scoff “I already do this.”

So did I.

It’s only when the intent behind these core principles matches our weight training intensity that the results are maximized. We program percentages and rep schemes and treat them like gospel, but things like plyometrics are usually an afterthought. When you look at your old workouts, how often are your athletes performing max effort or measured jumps? Does most of your running involve full speed trials or is it predominantly conditioning? Do your kids perform intentional deceleration work, or do you let “the game” take care of that?

If your goal is to build a powerlifter, then continue to neglect the athletic side of training. But if you want a team of elite athletes, you’re going to have to train them like elite athletes. Share on X

If your goal is to build a powerlifter, then continue to neglect the athletic side of training. But if you want a team of elite athletes, you’re going to have to train them like elite athletes.

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References

1.Myers, Thomas. Anatomy Trains. Churchill Livingstone: 2001.

2. Blumenthal, D. “NFL injury rate rises in 2020 as culprits range from Covid to turf.” Sportico.com. January 29, 2021. Retrieved from https://www.sportico.com/leagues/football/2021/nfl-injury-rate-rise-2020-1234621442/.

3. McInnes, S.E., Carlson, J.S., Jones, C.J. and McKenna, M.J. “The physiological load imposed on basketball players during competition.” Journal of Sports Sciences. 1995;13(5):387-397.

4. Hernandez J. L, Sabido R., and Blazevich A.J. “High-speed stretch-shortening cycle exercises as a strategy to provide eccentric overload during resistance training.” Scandinavian Journal of Medicine and Science in Sports. September 2021.