Over the last decade, not much of the sprint research has pointed out how athletes can improve. Instead, it has typically just added a few numbers to observations we are all familiar with as coaches. Contact length, pioneered by Jon Goodwin, is simply the most important variable in sprinting that is hardly talked about and rarely addressed. Countless debates have wasted time and emotional energy on the value of stride parameters, and for the most part, coaches have simply focused on splits and maybe jump tests.Though rarely talked about, contact length is perhaps the most important variable in sprinting, says says @spikesonly. Click To Tweet
This article is mainly about linear speed, but I will share some points on jumping and hurdling since this one variable is so meaningful in performance. Not everyone needs to worry about contact length, but if you do have the desire to fully maximize an athlete, focusing on the application of force on the ground is a wise idea.
What Is Contact Length Exactly?
Many coaches get confused when I mention applied or contact length, because the stride length and contact time are usually conjured. Earlier studies used the applied force period of time to describe a type of contact length, or the total distance on the ground from the center of mass to the foot that is in contact with the ground. Most commonly, coaches and scientists use the total length in meters or centimeters to summarize the event. Stride length is the distance between the oppositional foot strikes, and contact time is simply the duration the foot is on the ground.
All three measures are connected, but due to the requirements of measurement, contact length is less commonly discussed because it’s very difficult to even guess when someone is running over 40 kilometers per hour. Contact length is a summary of a sliver of action during a very narrow time frame: roughly 80-100 milliseconds.
Contact length is an interesting variable to coaches, but describing the details of stride parameters isn’t going to get people faster unless you know the other factors involved during the sprint. Contact length and contact time are very helpful, and stiffness of the stride is also important. Stiffness—specifically the vertical mechanical stiffness of the legs through the pelvis—is highly connected to contact length. With all of the stride data available, coaches can simply throw their hands in the air and just bring out a stopwatch or they can decide to address contact length realistically by doing a few video reviews in conjunction with sprint testing.
How Does Contact Length Influence Speed?
Perhaps the most important part of this article is why this measurement matters. To me, a flying sprint is the most important sprint test, as it requires prerequisite acceleration abilities and demonstrates global athletic potential.
In my old article on split conversions, I made it a point to show in table form how to change meters per second into splits of 10m. The reason is that most coaches want to know if an athlete can run faster, as time performances or races are assemblies of athletic potential. A bad start or an athlete managing a curve wrong can produce a poor time, but it’s usually not representative of a sprinter’s ability. Contact length explains how an athletic is creating speed, and other variables that are accessible can help drive smarter training decisions.Contact length explains how an athlete is creating speed, and is a great foundational measure, says @spikesonly. Click To Tweet
Contact length can immediately tell a coach if an athlete reaches out more and/or requires more distance to push behind them. Because it’s a total distance, contact length alone doesn’t provide much more information than a description of what happens during foot contact. However, if properly analyzed, it’s a great foundational measure.
If you remember one concept from this blog, let it be this: Each athlete will have a unique style and ability to apply force at high speeds, but winning and improving depend on augmenting what someone has through training and careful development. Contact length may not change or even need to change, but eventually coaches must determine what is holding an athlete back, and contact length details could spell the answer to improvement.
Whatever the style or composition of the stride, the end result of horizontal speed is a function of all of the small components adding up to project velocity. Contact length, while not heavily researched, is clear at maximal velocity but still an enigma during acceleration. It’s the job of coaches to sort out how training programs improve race results, and if racing develops actual top speed or simply better performance times.
Based on current data, an athlete’s kinematic style, along with their specific neuromuscular profile, explains how an athlete is running fast. What can be modified and what is likely genetic (read, stubborn) is the fork in the road a coach must navigate.
How Force Qualities and Anatomical Factors Interact to Create Speed
Coaches care about what is trainable, and what needs to be left alone. The grey area—what you might be able to change—is very wide and difficult to discern. What we know is that when a coach works with an athlete, they will likely work on what provides the biggest return on their investment with resources. That is strength and speed endurance on the training side, and posture and other more teachable areas.
- Limb length and skeletal structure are the easiest anatomical factors to connect to speed, as the stride length of an athlete relies heavily on how much distance they cover per step.
- Foot structure and function will speed up or slow down trajectories of force, along with recruitment of muscle groups. In the general population, the foot anatomy in velocity is not meaningful with submaximal speeds; in racing, it’s a significant factor.
- Muscle architecture and tendon structure have an impact in sprinting, and muscular contractions differ in timing and contribution based on how an athlete applies vertical and horizontal forces.
- Body composition is fairly obvious, as leaner athletes have an advantage, but so does the size and shape of local muscle groups. Larger bodies, as a whole, have harder times creating favorable power to weight ratios.
- Neuromuscular adaptations are also factors for an athlete becoming faster without getting stronger in the weight room. Some adaptations are so subtle they are barely noticeable over a career, but the science supports their value.
These factors, along with the way an athlete expresses their talents with the support or restriction of a coach, are the reason so many body types succeed with subtly different strides. Every athlete has a unique fingerprint or style, but the differences are extremely minor—worth mentioning, but not getting hung up on. The responsibility is to see if the style difference has substance, and isn’t just an arbitrary idiosyncrasy that could become a wild goose chase.
Force analysis with kinetic instrumentation solved the riddle of how athletes can get faster with less time available to touch the ground. Braking forces and repulsive forces must be balanced so an athlete can produce the maximal net force to push them up and forward. Some athletes have more oscillation and some have very little stiffness but compensate with longer contact lengths to offset those disadvantages. The net result is what matters most.
While each athlete may have a unique way to produce force and speed, norms do exist that show most sprinters are rather homogeneous in nature. There are outliers, but even those athletes are not extremely different when we look at the data. From the research, it’s clear that the rate of force production is connected to contact length and this shows up with both stiffness and contact time.Rate of force production is connected to contact length, and shows up in stiffness and contact time, says @spikesonly. Click To Tweet
It’s safe to say that we barely know why athletes are different at high speeds, so it may be a generation before we know how to get them faster. As of now, we know why an athlete is fast, but there is not enough developmental or longitudinal data to see how athletes evolve their stride with both kinetic and kinematic data.
Using Contact Length Measurements in Speed Training
Most of the information I have on contact length in sprinting is for maximal speed because acceleration is harder to evaluate, as each stride is different and the range of acceleration is far longer. While maximal speed is technically a few steps, great top speed benefits all performance, even in the 40-yard dash. The NFL Combine article from Dr. Clark was the final piece of evidence to support my claim.
Worry about getting fast first, then worry about maintaining it with conditioning later. You can’t do maximal speed work on the track without accelerating, and the rate of acceleration is far more trainable with sleds and weight room training than maximal speed. If you want to get deeper improvement, maximal velocity training has the better payoff in the end, but the key is to be patient, as it takes a little bit longer to see the benefits. Don’t feel that progress will be slow, as basic strength training and the right recovery will show up with improvements early, so focus on years after the first season.
Contact length and development paths to the athlete are about compromise and some decision-making on the style the athlete is comfortable with. An athlete often runs the way they do because they simply tap into what they have with abilities and use what they can. If their abilities don’t change much, technique and specifically contact length may not change. Little is known about how contact length evolves in a career, but physics can show how changes and improvements to net propulsion are possible.
There have been some recent discussions on stride details, like how much pushing and pulling occurs with different athletes. Contributions of muscle groups and stride mechanics are worth discussing only when you have evidence of change from the cueing and training, otherwise it is only good on paper. Theoretically, the contact length, contact time, and kinematics of stance and recovery should change and those changes must produce faster horizontal speed to be useful.
Front-side and backside mechanics are well noted in Ralph Mann’s book on sprinting, but the reason elites hit those numbers needs to be explained more rather than followed blindly. Due to the off-the-charts limb velocities in high-speed running, directly managing them is near impossible. Telling an athlete to dorsiflex when stride frequencies are nearly five per second is beyond futile—it’s borderline madness.
Longer contact lengths usually means longer contact times, and less stiffness. More stiffness means more frequency on average, but stride length may be slightly compromised. While all attributes of stride parameters interact, no perfect connection exists because sometimes some surprises occur with outliers. Making changes to one facet may not change other variables, or may ruin what was working in the first place. Nobody has the perfect answer, but simple testing and checking in from time to time are worth the extra effort if sprint performance is going to improve as a whole.All stride parameter attributes interact, but due to surprise outliers no perfect connection exists, says @spikesonly. Click To Tweet
Contact times, the duration of foot plant during sprints, is very short compared to the air time off the ground. The relationship is not necessarily inverse, but on average, if you have a hard time producing a large force quickly, you are unlikely to get much air. Some athletes have more vertical oscillation and have short contact times because they are able to create rapid stiffness of the hip, knee, and ankle. Other athletes can conserve speed by pushing their hips forward and having less vertical movement, but the best strides combine both qualities and produce efficient sprinting. Still, effective speed is the name of the game, as the fastest athlete rarely loses in a 100m.
Leg angles during first contact, mid stance, and toe off hint to how stiffness is gained and lost during high-speed running. Just because an elite has extreme high or low stiffness doesn’t mean that they should change those values or ignore them. What should be explored is how stiffness will improve or interfere with other gifts, like projection from early stance to slightly past mid stance. Remember: Sprinters contribute very little propulsion near toe off, so focusing on hip extension past the center of mass is too late, and most of the work during sprinting happens earlier in the landing phase of the stride.
How Contact Length Changes in Hurdling and Jumping Events
Stride length changes in sprinting are based on task, and clearing a hurdle or jumping horizontally will modify contact length to achieve the goal of going up and out versus moving fast into the next step. Available research shows that hurdling and jumping have enough similarities for commonalities to exist, but several stark differences are worth noting.
For example, stride length between hurdles is shorter due to the flight patterns of takeoff and landing, while contact times and contact lengths of long and triple jumpers are unique due to the demands of the horizontal events. We know far less about the contact lengths of hurdling, but we can easily collect them from video analysis using Dartfish and similar programs. Jumping events have a lot of information, due to the awareness of the penultimate step and how one foot plant can mean gold or not even being on the podium.
Jumping events and bounding in general have a common parallel, specifically in the amount of force and distance that work is done, after the center of mass. In the past, triple extension was praised as a successful quality of elite sprinting, but as better video and deeper objective analysis has shown, true full extension and triple extension are not the same. Full extension and pushing further back and longer doesn’t mean faster, as athletes like Asafa Powell and Tyson Gay demonstrate limited backside mechanics at top speed.
Bounding has different contact length measures than sprinting. Forces are transmitted through the ground more gradually and require longer contact times. Shorter contact times are not cardinal signs of being more effective in speed production, but on average, a shorter period of force is usually a good indication that the nervous system is adapting well.
Hurdling, especially the men’s high hurdles, requires shuffling at higher speeds, as the constraints of a 10-yard spacing forces the athlete to construct a stride pattern that fits the need of sustaining a fast velocity in and out of the barriers. The longer 400m distance and women’s hurdles have less contact length differences because the running is more like actual sprinting. Two reasons women have less technical demand with hurdles are that the hurdle height is lower and the athletes tend to be relatively shorter than their male counterparts. Tall hurdlers in male events are common, but short hurdlers in female events are the norm.
Training and Therapy Modalities That Influence Speed and Contact Length
Theoretically, two primary approaches drive changes to contact length, and they are mainly tissue and joint modifications from manual therapy, and training and mechanical enhancements from coaching. Ideally, both performance therapy and performance coaching can work side by side to create a synergistic change. However, for the most part we know very little about how contact lengths develop from coaching programs and how therapy may show up in sprinting mechanics.For the most part, we know very little about how contact lengths develop from coaching programs, says @spikesonly. Click To Tweet
Orthopedic evaluation of muscle length with table tests didn’t influence kinematic changes with gait analysis, but based on the experience of some therapists, this may be due to the athlete’s inability to take advantage of those changes and the population studied. Some athletes with very poor length have issues with overstriding and poor heel recovery, while others are surprisingly able to recreate the same fluid motions while scoring poorly on the set of Thomas tests.
My conjecture is that relaxation or tone is far more complex than a measurement on a goniometer, but tossing out the test entirely isn’t a good idea for sprinting at high velocities. At lower speeds, such as recreational running, the demands are not maximal, and this explains why some measurements have either no correlation or no chance of causation.
For the most part, soft tissue therapy can only manage tone, and suppleness without being flat is the goal of any method used in bodywork. During heavy training or even peaking periods, the right amount of tone is necessary to reduce injury and ensure that the tissue is responsive. While it’s hard to truly separate peripheral and central fatigue, the residual effects of overload are usually seen in drive (CNS), and soreness and stiffness (PNS). The right load and some complementary soft tissue work can help with recovery mechanics, thus reducing some overstriding that may not be necessary for athletes who have contact lengths that are longer than their peers.
Coaching is mainly a by-product of teaching and training, and instructing technique and improving technique from training are two paths that may or may not be distinct from one another. For the most part, blending training and teaching is necessary, as it’s nearly impossible to teach without some sort of effort and strain on the body. Even lower-speed running, such as tempo workouts, challenge the connective tissues of the lower leg, thus improving efficiency of the body and the chances of an athlete learning to move better at higher speeds.
Some drills, such as wicket patterns and high knee runs, provide motor skills and exposure to qualities that may address maximal speed indirectly, but they are not proven to influence speeds past 10 meters per second. Drills and exercises may support maximal speed, but without sprints at specific velocities, whether in practice or racing, faster top speed isn’t going to surface.
The primary training stimulus outside of sprinting is specific strength in the form of plyometrics or weight training. Beyond sprinting, not much research is available, and for the most part, jump training and some isolated work to muscle groups have merit. I warned specifically that horizontal exercises may not transfer to horizontal speed, but it’s always worth a try and contact length details may better prescribe workouts. Video analysis and contact grids might be the best ways to target specific needs, rather than painting too wide and applying methods that are not necessary or a priority.
Contact Length Applications and the Future
For now, contact length is a measurement that video does really well, and contact grids, in conjunction with good camera recordings, will add more insight to how athletes can get better. Legacy measures like stride frequency and air time are still relevant, but an added layer of knowledge with contact length moves understanding forward and assists with real-world application.#ContactLength measurement adds a layer of knowledge that moves understanding forward, says @spikesonly. Click To Tweet
Down the road, contact length will have more granularity in measurement and explain what influences the length of force application. With the right measurement tools and the right education, coaches can build better programs to achieve their goals.
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