By Bob Alejo
Certainly, we can agree on this: No one competes on a playing surface (field, court, pitch) where the ground moves! OK, surfers do. But on grass or dirt, the ground might give way but it doesn’t wobble to and fro, and it’s not enough of a prevalent part of sport to train on an unstable surface.
I’ve thought about this a lot over the years, mostly from a common-sense point of view. If common sense is part of what we do as strength and conditioning (S&C) practitioners, and specificity (muscular and neural) is so important, then why do we put athletes on wobble boards, BOSUs, or 3-inch foam pads and expect a significant carryover to a playing surface?! We’re not talking rehabilitation now. I understand the role of instability training at the right time. Strength and conditioning coaches don’t do rehab.
For me, rehab is what you do to get the athlete ready for return-to-play protocol, which for strength and conditioning is training. I thought that this would be a short, slam-dunk article, but as I dove deeper into the literature there was more than met the meta-analysis. There is no shortage of information on training in an unstable environment.
My Exhaustive Research Beyond the Gadgets and Balance Toys
As my favorite soul/funk band, Tower of Power, says, “Don’t change horses in the middle of a stream.” And that’s exactly what I did. Not that I now believe training on unstable surfaces is a good idea for strength and conditioning—it’s not at higher levels, as I’ll discuss later. However, my willingness to read more of the science on instability training led me to a greater understanding of it. At the same time, it supported my thoughts in specific areas and increased my knowledge in others.
Just so you know, this piece is not all opinion—although I certainly do add my hypotheses on some of my conclusions based on the science. I reviewed a bunch of the literature and ended up using 59 papers on the topic of instability training. To be clear, this was not a meta-analysis or a systematic review. This was me searching the literature for studies (abstracts, full texts), which also included reviews, systematic reviews, and meta-analysis.
To determine the studies I would use that were directly or indirectly pertinent to the topic of strength and conditioning, I broke down the literature I read into three main groups based on the subjects involved in the study: non-athletic, recreational, and athletic. Table 1 lists the categories and the descriptors included in that category. I used these descriptors to identify the subjects in the manuscripts. I excluded from the groupings—but not the findings or my subsequent interpretation—10 meta-analyses/reviews, one position paper (David Behm, PhD, 2010), one clinical commentary (Behm, 2012), one letter to the editor (Behm, 2015), and a very extensive article by Chris Beardsley, PhD (“Why are strength gains stability-specific?”), which is essentially one helluva review.
What Is Instability Training?
I use the term “instability training” because I needed a blanket term. Not all training happens on unstable surfaces nor is it just relegated to lower body methods. Upper body and core studies are part of training for stability because cables, TRX, and the like contribute to unstable modes as well. In the review, “Instability Resistance Training Across the Exercise Continuum,” Behm et al. (2013), summed up what instability training could entail, and it was reflective of the papers I reviewed:
“It can involve unstable conditions with body mass or external loads (e.g., dumbbells, barbells) as resistance. Instability can be induced with Swiss or BOSU balls (Team BOSU, Ashland, Ohio; a hemispheric inflated ball that is flat on one side and convex on the other), foam rollers, wobble boards, suspended chains, ropes, and bands. Natural surfaces (sand and gravel) can also provide an unstable training surface. Reducing the base of support (bipedal to unipedal stance) will also provide a challenge to the equilibrium (e.g., one-legged squats, Bulgarian squats). Unstable environments such as water can also provide a challenge to postural and joint stability resistance provides a disruptive torque to the body, contributing to instability challenges.”Stability training isn’t just stable or unstable; there are varying degrees of stability, says @Coach_Alejo. Click To Tweet
Although sand is as an unstable training surface, it is, as all of us well know, an often-used conditioning, speed, and training surface that has yet to be confirmed as significantly beneficial. Sure, coaches have their opinions and mention the (infamous) line, “It really works for us,” but the few studies I read before I decided to wait another day didn’t make me want to go out and buy tons of sand.
Truth be told, I wanted to include sandy surfaces as part of the instability discussion. However, after discovering at a bit more complexity than I originally thought with traditional instability methods, I thought it in the best interest of time to address sand at a later date. I’ll say this: In the end, the information available might prove there is more mechanical work done on sand, yet nothing that can really contribute to a trained athlete’s profile.
Clearly, there is more to instability training than a BOSU or Swiss ball. Nevertheless, those two balls and padded surfaces (like AIREX®) were the most commonly used unstable training platforms in the literature that I read. In addition to the previously mentioned lists, the papers that I read also mentioned balance pads, TheraBand products, T-BOW®, powerboards, whole body vibrations, proprioceptive discs, Aero-Steps, and balance cones. Yet, that is not the end of unstable conditions.
As Behm mentioned, bipedal and unipedal offer two types of stability—or instability as it were—not to mention the difference of free weight versus machines (track resistance). I ran into two terms I had not heard before: coupled and uncoupled (Campbell et.al., 2014). In this study, they used the terms to mean a barbell and dumbbells (DBs), respectively. I can see where even a bar connected to a cable (coupled) is more stable than two handles (uncoupled); both present different EMG challenges, including changing the stability of the surfaces an athlete performs the exercise on.
Undoubtedly, though I professed I do not do instability training, I have done it for a long time, albeit not for balancing or different EMG patterns. This is because much of normal training is barbell/dumbbell, one leg/two leg, and core-challenged tasks that have inherently different levels of instability. So I stand somewhat corrected.
On the other hand (I’m bailing myself out a bit), I remain unwavering in my belief that creating an unstable surface is not the best idea, and has never been for me. As you’ll see, perhaps not for you, either. The transfer is not there and, again, we don’t play on a ground that moves.
There are many layers to this. Let’s look at a continuum of some different stability environments that others have mentioned and use the overhead press as an example:
- Seated machine overhead press
- Standing machine overhead press
- Seated barbell overhead press
- Standing barbell overhead press
- Seated DB overhead press
- Standing DB overhead press
- Seated 1 arm DB overhead press
- Standing 1 arm DB overhead press
- Standing 2 DBs, one-legged overhead press
- Standing 1 DB, one-legged overhead press
We always talk about progression, and you could argue that each of these overhead presses has distinct and different effects on the body and its own level of instability, though none use an unstable surface. In these cases, the instability relies on the body’s own lack of stability by changing the center of balance with support symmetry, sitting or standing, bipedal or unipedal, coupled or uncoupled. To take it a step further, you could take No. 10 and have the DB be on the support leg side or non-support side to again give a different stimulus to the body.When you think about it, you really fight for balance through all exercises, says @Coach_Alejo. Click To Tweet
Each exercise contributes to important physical improvements—that is to say, important physical improvements based on the S&C coach’s philosophy, athlete’s needs, time of year, and so on. A coach could choose all the exercises, four of them, or none of them, depending on their goals. Or, as is sometimes the case, use the exercises while misinterpreting how they pertain to the goals.
Stability training is just not stable or unstable, as you can assume by now. When you start putting some thought into it, of course there are varying degrees. Organizing how you want instability training to look is important for a disciplined approach. In the article previously noted, Beardsley put stability into three categories, which was very helpful for me understanding the science:
“External load stability exists on a continuum from very stable to neutrally stable to very unstable.”
Respectively, his examples were barbell bench press on a bench, dumbbell bench press on a bench, and dumbbell chest press on a Swiss ball. Now you can see a few things here. Very stable doesn’t mean totally stable, which makes sense. Even though the bench press on a bench is a pretty solid foundation, a slightly uneven spotter’s lift-off or raising one leg off the ground shows that “very stable” is so close to being unstable. Also, dumbbell training appears to be slightly unstable no matter the exercise.
It’s easy to understand how a DB overhead press can be slightly unstable, but when you think about it, you are really fighting for balance through all exercises. In other terms, think of a machine overhead press and how there is almost no, if any, balance or feeling of instability versus the same movement of a DB overhead press. This thing has plenty of layers.
The EMG Science Behind Instability Training
What is actually happening? There are too many different studies involving too many different muscles to specifically account for. It’s not always possible to summarize, as Andersen V. et al. did in their study in 2014: “The muscle activity was greater in the biceps femoris (63-77%, p<0.01) and core muscle external obliques (58-62%, p<0.05) for the Bulgarian squat compared to regular squats, but lower for rectus femoris (16-21%, p<0.05).” It would simply take too long for the numerous studies out there.
However, what popped up most in the studies I read is a comparison of electromyographic (EMG) analysis in stable and unstable environments—peak activity and greater/lesser activity assessments. Essentially, researchers looked at muscles thought to be active in each movement and found out exactly what is going on; usually stable versus unstable and with varying loads (relative or absolute) in either environment. Most studies appear to show that EMG increases under unstable conditions and is similar to many cases when performing exercises in a stable environment.
This makes sense, as your body calls on all muscles to help stabilize and maintain balance when things are not stable. This is where the terms “prime movers,” “stabilizers,” “agonists,” and “antagonists” enter the picture in abstracts and the bodies of manuscripts.
Under moderately unstable (notice the word “moderately”) conditions, stabilizers, agonists, and antagonists may all activate as a primarily protective mechanism against injury for the joints, muscles, or tendons. A co-contraction of an agonist and antagonist was explained to me as a “stiffening strategy,” again describing the body’s safety mechanism. However, when the instability is too demanding, the prime mover (agonist) has a lower-than-normal EMG. Basically, when the athlete is trying like hell not to fall down, there is not much benefit to the drill/exercise. This is the reason I can only say most studies show EMG increases instead of all studies.
An antagonist does not have to be a stabilizer and could show less activity depending on the level of stability present in the study. In the Andersen study I spoke of, they concluded that the Bulgarian squat “was advantageous for the antagonist and somewhat for core muscles” because the rectus femoris (agonist) was less involved than with regular squats, probably due to the instability difference between regular squats (bipedal) and Bulgarian squats (unipedal).
I’d say the EMG reporting of training in an unstable environment (increased EMG activity, increased co-contraction and stabilizers) laid the groundwork for rehabilitation theory, and that theory seeped into S&C somehow—as in: If we can get more muscles activated then we will get greater force production and therefore more power and, of course, our athletes will improve their ability to balance as well. Ergo, if an athlete can bench press or squat while trying to balance the load and their body then they will move even more load when the training is under stable conditions, right?! Uh, no, it’s not that simple at all.
This leads me to believe that most coaches have an even more basic assumption that if an athlete practices balancing when lifting weights, the result will be an increase in strength and better balance on the playing field. Here again, it ain’t that simple! Certainly not in the S&C world. It’s really quite the contrary, in many instances.
Most Studies Involved Non-Athletic and Recreational Populations
Dr. Behm and I talked at length on the topic in general and he was generous with his findings, hypotheses, and science on the topic. He agreed that what I had found is a fair assessment of the literature in that there was not enough work done on higher-level athletes and certainly not elites. Even though I found eight papers that I could characterize as work done with athletes, only three were collegiate level athletics and only two of those were described as DI.
Four papers used the term “elite,” but personally, I’m not sure they meet the criteria. One study had their elite athletes’ mean age at 16.6 years old, with a standard deviation of 1.1 (Prieske et al., 2016). One described their athletes as elite in the text, but as subjects noted them as “college, DI players” (Cressey et al., 2007). The third study used the term “sub-elite” (I’ve not heard of that one) and subjects 15 years of age as the mean (Granacher et al., 2015).
Certainly, we could consider them part of the athletic population; nevertheless, I’d say that “elite” is unlikely. Frankly, people toss around “elite athlete” way too casually without an understanding of the term, or purposely (a practitioner trying to paint a picture of their own experience or skill level) and shouldn’t be. My interpretation of elite is “world class.” By that, I mean one of the best in the world at what they do.
Short rant ensuing: A very rare few of collegiate athletes are world class (elite). Even some professional athletes who dominate their sport but whose sports are not played worldwide, really cannot be deemed world class. Now, an athlete of any sport—or age, in some cases—can have world-class speed, strength, power, or vertical jumps. Those numbers are easy to find for comparison, leaving little argument. However, those qualities alone do not make them world class athletes. World class has been decided and defined. Let’s leave it at that.
Research on instability training of collegiate, professional, and elite athletes is scarce compared to other sample sizes, therefore rendering the data somewhat cloudy in terms of specifics. Cloudy because there isn’t enough information that says it’s a “must have” in an S&C program at that level. Furthermore, based on the amount of research out there, I’d say the implication is that it’s not that interesting to researchers, and coaches have not seen anything that makes them push for more studies.
In other words, conventional wisdom would say that if an unstable environment is a great alternative (safe, effective) for improving a collegiate, professional, or elite athlete’s strength and power, and has great carryover to athletic performance and injury management, then certainly we’d see more research in that population. Results from those studies would clearly show significant benefits, researchers would do more work on it to prove or disprove previous findings, and on and on. For example, we see much research on bands, chains, and velocity-based training (VBT) because the data shows benefits worth looking into for any additional advantages or derivatives.
As a fair assessment of the amount of research on the athletic population, I understand a coach’s or researcher’s predicament when gathering subjects. Especially when the subjects are in a highly competitive environment, which most likely means they are on a comprehensive, rigidly scheduled training regimen. It’s pretty tough to tell any team at the highest level—or convince the coach—that 10 athletes will be on a program that uses lighter-than-normal weights and produces less power and force. Also, that another 10 athletes will do proven strength and power methods that will likely result in improvements in speed, vertical jump, and strength!
Not that you couldn’t learn from the existing information or the data on non-athletes and recreational subjects: All the data is useful. In fact, the results from the other groups indirectly tell a story about the pros and cons of unstable environments for the highly trained and skilled population. And a method doesn’t necessarily have to have extensive research to be beneficial; it could be in the beginning stages of cementing the evidence in place. However, that doesn’t change the fact that the most researchers use non-athletic, recreational groups for their research.
Instability Training and Improvements in Performance
What do I mean by performance? Certainly not yards-per-carry or batting average, although at some point folks, we have to at least run correlation coefficients to get some idea of whether what we are doing works. For my sake here, performance measures are no different than the normal battery of tests that S&C should run: vertical jumps, short sprints (10-20m), standing long jumps, agility tests, and Y Balance tests. The reality is, if my review reflects the literature, then measuring performance after training under unstable conditions is not abundant.
Granacher’s 2015 study has a pretty complete testing battery (CMJ and drop jump, multiple bound test, 0-30m sprint time, figure-8 run time, postural sway during one-legged stance, SEBT performance, platform oscillations following a perturbation impulse), and a 16-plyometric exercise menu performed under stable and unstable modes. Remembering the average age of the participants was 15.2 years for the unstable surface group and 15.6 years for the stable, there were similar gains in speed, agility, and balance in both training programs. This illustrates there was no benefit in adding instability to the training. However, there was a better CMJ from the stable group than from the unstable.
Prieske (2016) did a similar study with a group whose average age was basically one year older, on in-season soccer core training combined with weight training. Subjects performed identical core training exercises under stable and unstable conditions. Here again, both groups improved their performance but the improvements were similar, showing no additional benefits with unstable training.#UnstableTraining doesn’t allow for enough loading to create strength and data, says @Coach_Alejo. Click To Tweet
Looking at collegiate athletes, Cressey (2007) studied predicted power output, sprint, agility, and jumps, and pre-test and post-test of lower body training in stable and unstable environments. Essentially, even though both groups improved in some instances, the stable surfaces group outperformed the unstable group in all categories. So much so that it led the authors to conclude that the results of their study affirmed—what was a criticism then and now is fact—that unstable training does not allow for enough loading to create strength and data. They said that it: “…also demonstrate[d] that UST (unstable surface training) actually attenuates power (and presumably strength) gains derived from concurrent stable surface training.”
As I said earlier, there was not much on performance testing from what I gathered. But just in case, I went back to see if I could find additional performance studies and, when I did, no shortage of core-related studies popped up. Again, after reading several papers, I chose to use the systematic review of Reed et al. (2012) to summarize the lion’s share of what I saw. Although, their study was not exclusive to instability training, it certainly summed up what the science and general thoughts on the research say. Per their abstract:
“In the majority of studies, core stability training was utilized in conjunction with more comprehensive exercise programmes. As such, many studies saw improvements in skills of general strengths such as maximum squat load and vertical leap. Surprisingly, not all studies reported measurable increases in specific core strength and stability measures following training. Targeted core stability training provides marginal benefits to athletic performance.”
Taking it a step further and going slightly off topic, as we hear about core training all the time, I’d like to add what Hibbs et al. (2008) state in their abstract about core stability and strength. We all know the value of being strong “in the middle,” but to say someone needs more core strength to run faster or jump higher is a little narrow-minded. Should we believe that a strong and stable core contributes to athletic performance? That’s an easy one—of course—and no one believes a weak core is a great asset. On the other hand, don’t expect core training to be a game changer. Nothing powerfully suggests that core training improves performance.
“A further confounding factor is that because of the differing demands on the core musculature during everyday activities (low load, slow movements) and sporting activities (high load, resisted, dynamic movements), research performed in the rehabilitation sector cannot be applied to the sporting environment and, subsequently, data regarding core training programmes and their effectiveness on sporting performance are lacking.” (Hibbs et al., 2008)
At the expense of this article taking way longer than it should and based on enough information (listed or read) to suggest that, regardless of chronological training age or skill level, instability training with or versus traditional weight training exercises shows no significant advantage for improving athletic performance, I stopped looking. Trust me—there was no damn way I was going to list every study I read to prove an obvious point. Most of the science is crystal clear in this area. And, a well-timed email to Dr. Behm regarding my theory confirmed that, in fact, most studies support my assumptions.
Instability Training and Improvements in Strength and Power
Strength, power, and force production have shown some interesting results for the S&C community. Again, keep in mind that I’m not saying—nor does the literature, at times—that there is no benefit to instability training. For the S&C coach trying to gain a performance advantage by way of strength and power, the studies and reviews consistently show that there are limited or lowered benefits when training in an unstable environment, and this is perhaps even less effective with a trained or elite population.
One of Dr. Behm’s several reviews looked at the results of strength, power, and balance across age groups (Behm et al., 2015). The meta-analysis showed that while training on unstable surfaces improved strength, power, and balance compared to a control group (no training or regular training only), “the performance of STU (unstable surfaces) compared with STS (stable surfaces) had limited extra effects on muscle strength, power and balance performance in healthy adolescents and young adults.”
Zemková et al. (2012) looked at upper body (bench press) and lower body (squats) power outputs on BOSU and Swiss balls compared to stable. They concluded that power outputs were, in their words, “profoundly compromised” during resistance training under unstable conditions as compared to stable.
Chulvi-Medrano (2010) looked at both muscle force and activation during the deadlift under stable and two different levels of unstable conditions. They had this to say in the discussion section of their manuscript: “Taken together, our data indicate that the execution of deadlifts in unstable conditions decreases physical performance and generates a lesser stimulus on the paravertebral musculature than the same exercise performed in stable conditions.”My hypothesis is #instabilitytraining has little benefit at the collegiate, pro, or elite level, says @Coach_Alejo. Click To Tweet
Across the board, there was an overwhelming conclusion in the literature that training with unstable conditions leads to lower muscular force and power production. Again, this does not mean that there was zero force or power produced or that other populations could not benefit from it. Yet, the ineffectiveness shown in other populations leads me to a strong hypothesis that instability training provides little benefit at the collegiate, professional, or elite level.
Why Unstable Conditions Aren’t Beneficial for Collegiate, Professional, and Elite Athletes
After a lead-in like that, the question could be, “Then what is it good for?!” Once more, I’ll take an opportunity to say this article is about training in unstable environments and how that affects the trained population, which is, for the most part, the athletes we work with. Ironically, some of the reasons I will give against leaning heavily on instability training for improvements in performance are the very reasons that it is perfect for adolescents, injured folks (athletes or otherwise), and older adults (>60yrs of age). My guess, based on the training age, is that children will gain power, strength, and balance with unstable training, but not much has been done with that group.
There is no question that, given the right load and level of instability (relative to stable loads, not absolute), there is the same or greater muscle activity than a stable environment. We do see some improvements in performance, strength, and power as an effect of training in unstable conditions, just not as much as we see in stable environments. Instability training is not bad and given the right population it could be very beneficial, just not typically to the trained athlete and here’s why:
Unstable surface = Lighter weights
The majority of the studies showed subjects had to use lighter weights in the unstable condition when comparing exercises. In other words, in bench press studies, the weights used in the unstable condition were always lighter when the load was significant and they needed a comparison, which is the reason they used relative loads instead of absolute loads. For our purpose, the heavier loads are the loads where there is muscle production, strength gain, and power production.
It is a waste of our time to do the same exercise with a weight that does not promote optimal physical characteristics just to do it without stability. Common sense tells us that light weights don’t get athletes strong; this definitely leads to less strength, no matter the improvement. And, if the repetition zone does not match the weight, then the weight won’t be heavy enough to create muscle. Simply put, athletes can handle heavier weight under stable conditions versus unstable conditions.
Reduced Force Outputs Result in Less Power
The predominant theme of the training data analysis under unstable conditions is the striking reduction in force and, subsequently, power. It would be of no surprise then that the speed of motion, as well as the range of motion, were negatively affected under unstable conditions, as cited in the literature. A key phenomenon in the reduced force outputs of training unstable is what helps to reduce the risk of injury and makes instability training great for rehab: co-contraction of musculature. Usually, this is what happens under unstable, but not severe, conditions.
As pointed out before, if there is too much instability, EMG is reduced in musculature, not increased. Simultaneous contraction of agonists, antagonists, and stabilizers increases the joint stiffness and leads to a more stable joint. This a terrific environment for rehabilitation—lighter weights and reduced force requirements for a body part that is not yet healthy. Unfortunately, from a performance standpoint, this is the last thing that you want to have happen.
Even though co-contraction is a safety mechanism, “…it would also contribute to force deficits during unstable conditions by providing greater resistance to the intended motion.” (Behm et al., 2012). Now we know that not only is the weight lighter when performing exercises in an unstable mode, but athletes also typically move it slower and in a reduced range of motion. It’s not difficult to understand how the outcome of that type of training won’t bode well for trained athletes.
Many studies show that untrained individuals make good improvements when training on unstable surfaces. First, most studies utilize untrained recreational subjects (who volunteer), so the sample sizes and amount of data are ample. As I say, if there was more research on the topic, I bet children would be in the same boat.This analysis shows what you already know: Untrained subjects will improve doing nearly anything, says @Coach_Alejo. Click To Tweet
All this analysis tells you what you already know: Untrained subjects will make improvements while doing pretty much anything. I would also group college freshmen in this category. If someone was to point out to me that they could make the same gains performing in an unstable environment, I would respond by saying that following the unstable training block I’d have to re-teach them in the stable environment. The loads would be much heavier performing the same exercises and pose an injury risk. They’d have so much body soreness that I’d have to be very cautious of the loading and repetition scheme, and spend at least four to six weeks catching up to where they should’ve been in the first place! What a waste.
Stable Work Transfers Better Than Unstable, Especially for Ground-Based Performance
Specificity is a word that I have disdain for because of how people in sport use and define it. My take is that exercises are either 100% specific to athletic performance or 100% not. Contact me if you want to chat.
However, that’s not the context that science lends to ground-based performance. I like the way Beardsley uses the term “stability-specific.” I can see where there is a certain stability to all exercises that we use, including drills. In this case, performance is stability-based in that most studies on the topic—and there aren’t a lot—say that lower body training on stable surfaces gets better results (jumps, sprints, and agility) than on unstable surfaces.
As an example, lower body training (squats, single-leg squats) on a stable surface (the ground) resulted in better performance measures than the same exercises performed on unstable surfaces. This was similar to the methods and conclusion of the Cressey study mentioned earlier. In this instance, specificity is much like I stated in the first paragraph: If we don’t play on unstable surfaces, why would we train on unstable surfaces, especially with healthy athletes? Knowing this, no coach could, in good conscience, opt to do an exercise or method proven to achieve underperformance.
Free Weights vs. Machines Are Also a Stability Issue
Generally, machines are more stable than free weight movements. That said, machines can still contribute to free-weight-tested strength. Beardsley had an interesting statement in his manuscript: “Without exception, every single study has shown that training using machines can improve strength tested using free weights.”
As for the contribution to performance: No, machine training is not as good as free weight training—that’s proven. However, machine training (leg press, Smith machine, leg extension) has shown to improve performance, thereby dispelling the myth that there is no carryover to performance. Although there isn’t as much improvement as free weight training on the ground, it’s not a waste as an interim alternative.
Now that we have that out of the way, I believe this with every ounce of my career: Every S&C facility should have a line of selectorized or plate-loaded machines for the very reason they say that machine-based training doesn’t carry over well to the field. Its “track resistance” means there’s no need to balance the load and therefore limits the activity of the antagonists and stabilizers. The stability of a machine (cables are considered slightly unstable) is a great alternative for focusing on lagging body parts that lack size or strength; during an injured period where walking around with dumbbells or barbells (lower body injury) is risky; or for when a hand, wrist, or elbow injury limits free weight training.
You Want Instability? Use DBs, Cables, Lunges, Hurdles, or Staggered Positions
All of these implements or modes add instability to exercises. But let’s step back for a moment. Is there anything less stable than watching a college freshman or incoming athlete bench pressing for the first time? Squatting, DB incline bench, deadlifting, DB rowing?! Those athletes are performing exercises under unstable conditions and it supports the science—light loads, less speeds, co-contraction, all putting less stress on the musculature and reducing the possibility of joint damage. It’s a good guess that EMG activity is more abundant than it should be. Later, when their technique improves, neural patterns improve; firing sequences are better; and there is less co-contraction, more weight, and more speed. In summary, there is no need to add instability to this group—they will provide it for you!
Video 1. The Single Leg Cable RDL provides a balance component and a loading benefit to athletes. More stability demands will diminish the value of the exercise, as the mechanical loading benefits get lost by the decrease in neuromuscular drive.
Take a team and have them stand on one leg on flat ground with the opposite knee at waist height and you’ll to instability training. The visual is a bunch of athletes having trouble standing on one leg with no external stimulus other than themselves and the ground. Next, have them take the unsupported leg and move it laterally, forward or backward. Have them move one arm overhead with the opposite arm remaining at their side, then both arms straight out front, and then overhead. This is all instability.
Now the million-dollar statement: Unless your athletes have a simple mastery of balancing on one leg, standing on a foam pad or BOSU will not make them better! Common sense tells you that if an athlete does not jog well, a sprint program will not improve the jog and sprinting will be somewhat fruitless. If two-legged, repeat long jumps look slow and imbalanced then one-legged bounding is a mistake. Who would make something more difficult and expect the execution to improve?If your athlete hasn’t mastered balancing on one leg, #instability devices won't make them better, says @Coach_Alejo. Click To Tweet
My following statement is for those of you that just plain dismiss the science because you “feel” or “believe” that, despite the literature and what it infers, training on or with unstable modes is still a great idea with collegiate, professional, or elite athletes. After researching for this paper, I am confident I can perform movements on solid ground for greater gains in strength and power, yet sparingly use different positions and modes on the ground that have degrees of instability (lunge position cable rows, one or two arms; one-arm cable RDLs; hurdle position overhead presses; staggered position Pallof Presses; unilateral DB step-ups) and still achieve my philosophical training goals with higher-level, trained athletes.
Final Thoughts Before We Lower the Instability Coffin
Finally! Talk about going down a rabbit hole! But I think it’s important because I still see and hear of coaches implementing unstable strategies with higher-level athletes, expecting outcomes that just won’t happen.
As a rehabilitative measure and training plan for children and older adults, instability training is a terrific idea that will bring about good results in strength and balance in just the right population. However, for us—strength and conditioning professionals looking for performance outcomes—it’s abundantly clear that if you train collegiate, professional, or elite athletes (collegiate freshmen may be the lone exception), training on stable, fixed surfaces for power and strength is far superior (as in, not even close) to training in an unstable environment. Fortunately for all of us, it can’t be said or written better than that!
*A monstrous round of applause and great thanks to Dr. David Behm. His mentoring, timely responses to my communications, and look at this article’s rough draft gave me all the confidence necessary to say this is a comprehensive article on instability training that will benefit the strength and conditioning profession. This piece would be less without his help.
A thank you also to Javier Del Sol, NC State S&C intern, for his help in the literature search for this article.
I also suggest that all of you read Chris Beardsley’s review. Again, it covers most of the stability-specific strength questions, and serves as a one-stop shop for stable/unstable questions from machines to barbells to dumbbells to unstable surfaces, with plenty of references.
- Andersen, V., Finland, F.M., Brennset, O., Haslestad, L.R., Lundteigen, M.S., Skalleberg, K., & Saeterbakken, A.H. “Muscle activation and strength in squat and Bulgarian squat on stable and unstable surface.” International Journal of Sports Medicine. 2014; 35(14): 1196-202.
- Beardsley, C. “Why are strength gains stability-specific?” Strengthandconditioningresearch.com
- Behm D.G., Anderson K., & Curnew R.S. “Muscle Force and Activation Under Stable and Unstable Conditions.” Journal of Strength and Conditioning Research. 2002; 16(3): 416-422.
- Behm, D.G., Drinkwater, E.J., Willardson, J.M., & Cowley, P.M. “Canadian Society of Exercise Physiology position stand: The use of instability to train the core in athletic or non-athletic conditioning.” Applied Physiology, Nutrition and Metabolism. 2010; 35(1): 109-12.
- Behm, D., Muehlbauer, T., Kibele, A., & Granacher, U. “Effects of Strength Training Using Unstable Surfaces on Strength, Power and Balance Performance Across the Lifespan: A Systematic Review and Meta-analysis.” Sports Medicine. 2015; 45(12): 1645-69.
- Behm, D., & Sanchez, J.C.C. “The effectiveness of resistance training using unstable surfaces and devices for rehabilitation.” The International Journal of Sports Physical Therapy. 2012; 7(2).
- Behm, D., & Sanchez, J.C.C. “Instability Resistance Training Across the Exercise Continuum.” Sports Health. 2013; 5(6): 500-503.
- Campbell, B.M., Kutz, M.R., Morgan, A.L., Fullenkamp, A.M., & Ballenger, R. “An Evaluation of Upper-Body Muscle Activation During Coupled and Uncoupled Instability Resistance Training.” The Journal of Strength and Conditioning Research. 2014; 28(7): 1833-8.
- Chulvi-Medrano, I., Garcia-Masso, X., Colado, J.C., Pablos, C., de Moraes, J.A., & Fuster, M.A. “Deadlift muscle force and activation under stable and unstable conditions.” The Journal of Strength and Conditioning Research. 2010; 24(10): 2723-30.
- Cressey, E.M., West, C.A., Tiberio, D.P., Kraemer, W.J., & Maresh, C.M. “The effects of ten weeks of lower-body unstable surface training on markers of athletic performance.” Journal of Strength and Conditioning Research. 2007; 21(2): 561-7.
- Hibbs, A.E., Thompson, K.G., French, D., Wrigley, A., & Spears, I. “Optimizing performance by improving core stability and core strength.” Sports Medicine. 2008; 38(12): 995-1008.
- Kibele, A., Granacher, U., Muehlbauer, T., & Behm, D. “Stable, Unstable, and Metastable States of Equilibrium: Definitions and Applications to Human Movement.” Journal of Sports Science and Medicine. 2015; 14(4).
- Kohler, J. M., Flanagan, S.P., & Whiting, W.C. “Muscle activation patterns while lifting stable and unstable loads on stable and unstable surfaces.” The Journal of Strength and Conditioning Research. 2010; 24(2): 313-21.
- Granacher, U., Prieske, O., Majewski, M., Busch, D., & Meuhlbauer, T. “The Role of Instability with Plyometric Training in Sub-elite Adolescent Soccer Players.” International Journal of Sports Medicine. 2015; 36(5): 386-94.
- McBride, J.M., Cormie, P., & Deane, R. “Isometric squat force output and muscle activity in stable and unstable conditions.” The Journal of Strength and Conditioning Research. 2006; 20(4): 915-8.
- Prieske, O., Muehlbauer, T., Borde, R., Gube, M., Bruhn, S., Behm, D.G., & Granacer, U. “Neuromuscular and athletic performance following core strength training in elite youth soccer: Role of instability.” Scandinavian Journal Medicine Science and Sport. 2016; 26(1): 48-56.
- Reed, C.A., Ford, K.R., Myer, G.D., & Hewett, T.E. “The Effects of Isolated and Integrated ‘Core Stability’ Training on Athletic Performance Measures: A systematic review.” Sports Medicine. 2012; 42(8): 697-706.
- Zemková, E., Jeleň, M., Kováčiková, Z., Ollé, G., Vilman, T., & Hamar, D. “Power Outputs in the Concentric Phase of Resistance Exercises Performed in the Interval Mode on Stable and Unstable Surfaces.” Journal of Strength & Conditioning Research. 2012; 26(12): 3230-6.