Unstable Silliness Training!
Unstable surface training is common training intervention used in gyms and rehabilitation facilities world wide.
The debate for or against unstable surface training can be a tough one to get into because it has typically been my experience that those who are using these methods don’t really have a good training/rehabilitation methodology or order of exercise progression. There is no real “thinking” involved in the application of these exercises in a training program. Rather, they are just thrown in because they are “hard” and because of this the client “thinks” they are getting more out of it.
Commonly in rehabilitation settings, where most of the research on unstable surface training has been conducted, clinicians will try and advance patients to these exercises too quickly, rather than having them develop sound movement patterns on the ground, before trying to progress to a more difficult variation of the basic movement.
Squats and lunges don’t typically look better on an unstable surface, so if your technique is crap when you are on solid ground, it wont get any prettier when standing on a wobble board. Crap in = Crap out.
Before I continue, it is important that we pause here to review our SAID principles:
Basically, we get what we train for. Balance and coordination are important aspects of athletics; however, these qualities are also highly specific to the sport in question. If we want to be better at running, cutting and decelerating, then we need to train those tasks. If we want to be better at performing squats on a bosu ball, then we need to squat on a bosu ball. Because adaptation is specific to the demands we impose on our bodies, it would be silly to think that squatting on a bosu ball would aid our ability to squat on the floor, or perform any athletic movement more proficiently.
As stated earlier, a lot of the information regarding unstable surface training has been conducted on athletes who are either injured or recovering from injury. Obviously, if we are a trainer or strength coach, applying research conducted on pathological populations to healthy populations doesn’t seem to pan out.
Additionally, studies still seem to be conflicting on the true benefits of unstable surface training and with the different types of surfaces available (bosu, wobble board, dyna disk, airex pad, etc.), you may get a different result depending on what you use. This seems to be more apparent in highly resistance-trained individuals, where moderately unstable training devices (IE dyna disk, bosu ball, etc) do not produce enough of a challenge to the nervous system.
What about my CORE!!
Increased “core” strength is a common quality that individuals using unstable surface training are trying to seek.
A recent study looked at core muscle activity (rectus abdominis, external/internal oblique, transverse abdominnus, erector spinae) during four exercises – back squat, deadlift, overhead press, and curls; performed under three different trials:
- On the ground with 50% of 1RM
- On a BOSU Ball with 50% of 1RM
- On the ground with 75% of 1RM
(Note: No lifts were performed on the BOSU at 75% intensity because exercises performed on an unstable surface offer a challenge to balance that would make lifting higher intensities potentially dangerous. Therefore, lifts performed on unstable surface are relatively submaximal in comparison to those that are commonly done on the ground.)
The exercises performed on the BOSU ball failed to produce significant differences in core musculature activity in all lifts when compared to exercises performed on stable ground with 75% intensity. Additionally there were no significant differences reported between the BOSU ball exercises (at 50% of 1RM intensity) with any of the exercises performed on stable ground with 50% intensity. The only significant differences noted were between the overhead press and curl performed on stable ground at 75% intensity and the BOSU ball, with the 75% intensity training showing higher activity of the rectus abdominus during the overhead press and the curl showing higher activity in the transverse abdominis and internal obliques. This led the researchers to conclude, “The current study did not demonstrate any advantage in utilizing the BOSU Balance Trainer. Therefore, fitness trainers should be advised that each of the aforementioned lifts can be performed while standing on stable ground without losing potential core muscle benfits.”
Strength And Sports Performance?
As noted above, one of the issues with unstable surface training is that appropriate intensity needed to develop strength cannot be reached due to the balance challenges that performing an exercise on something unstable present. While these balance challenges may be thought of as beneficial, it is important to keep in mind that balance is task specific, and developing appropriate strength is a crucial aspect of training (additionally, as seen in the above study, the challenge to balance didn’t add anything beneficial to the training interventions tested).
McBride et al, looked at force output between an isometric squat performed on a stable and unstable surfaces (balance discs). The isometric squat was chosen so that the subjects could perform the squat on a force plate, where force output could be properly measured. As to be expected, squatting on an unstable surface significantly reduced peak torque and rate of force development. This led McBride and colleagues to conclude, “In terms of providing a stimulus for strength, no discernable benefit of performing a resistance exercise in an unstable condition was observed in this current study.”
These findings are in agreement with Cressey et al who compared unstable surface training to stable surface training in a 10-week training program for Division 1 soccer players. The athletes in both groups performed the same training program except the unstable surface training group performed some of their lower-body exercises on a dyna-disc (small inflatable disc). The stable training group significantly improved their power output in both the broad jump and countermovement jump when compared to the results of the unstable surface group. Additionally, the stable training group significantly improved their 40-yard time compared to the unstable group and had greater trends toward improvements in their 10-yard sprint time as well. Cressey et al, concluded, “These results indicate that unstable surface training using inflatable rubber discs attenuates performance improvements in healthy, trained athletes. Such implements have proved valuable in rehabilitation, but caution should be exercised when applying unstable surface training to athletic performance and general exercise scenarios.”
While there are some studies that show evidence that unstable surface training can have a positive impact on balance (both static and dynamic balance), it is still not certain whether this will have a direct translation to improved athletic performance and skill. As stated earlier, balance is highly specific to the task at hand. Performing exercises on an unstable surface make you better at performing exercises on an unstable surface. It remains to be seen whether this type of training intervention will make you better at playing a particular sport.
If you choose to use unstable surfaces in your training programs, I urge you to come up with sound reasoning and progressions – making sure the client/athlete has appropriate technique on stable ground first – before just throwing this training technique out there, as so many do.
This article reflects my views on unstable surface training based on the things that I have read. I don’t have all the answers, but I can tell you one thing…I am not in a hurry to run out and buy BOSU Balls, Dyna-discs, or wobble boards. I’ll stick to good ole’ fashioned strength training for now.
Wahl MJ, Behm DG. Not All Instability Devices Enhance Muscle Activation In Highly Resistance-Trained Individuals. J Strength Cond Res 2008;22(4):1360-1370.
Willardson JM, Fontana FE, Bressel E. Effect of surface stability on core muscle activity for dynamic resistance exercises. Int J Sports Physiol Perform. 2009 Mar;4(1):97-109.
McBride JM, Cormie P, Deane R. Isometric Squat Force Output And Muscle Activity In Stable and Unstable Conditions. J Strength Cond Res 2006;20(4):915-918.
Cressey EM, West CA, Tiberio DP, Kraemer WJ, maresh CM. The Effects of Ten Weeks Of Lower-Body Unstable Surface Training On Markers Of Athletic Performance. J Strength Cond Res 2007;21(2):561-567.
DiStefano LJ, Clark MA, Padua DA. Evidence Supporting Balance Training In Healthy Individuals: A Systematic Review. J Strength Cond Res 2009;23(9):2718-2731.
Yaggie JA, Campbell BM. Effects Of Balance Training On Selected Skills. J Strength Cond Res 2006;20(2):422-428.