The Stability Ball Conundrum - Are They Actually Benefiting Us At All?

The definition of stupidity

The definition of stupidity

At some point over the last few years, unstable surface training received a significant increase in popularity.  Suddenly you cant walk two steps into a gym without stumbling into an inflatable exercise ball, BOSU ball, or weird squishy disc.

They are often considered a ‘functional exercise’ tool, whatever that means. But what a lot of people may not realise is that they started out as a rehabilitation based training tool, mainly to rehab various degrees of ankle sprains (which has shown to work, I might add).

Their gradual movement into the commercial gym setting was likely a result of the success they saw in this rehabilitation setting, and are now spouted as a sure fire way to increase balance and stability.

Now, I’m not denying that they may have the capacity to improve upper body stability (scapular stability in particular), and trunk stability in appropriate situations, but in my personal opinion that is where their benefits as a training tool for the general population stop. 

There are a couple of reasons i say this.

They have zero (and I mean ZERO) specificity to the real world.

Specificity implies that to become better at a particular exercise or skill, you must actually perform that exercise or skill. In the same light, if you practice a skill, you will get better at that skill.

So if you practice training on an unstable surface you will get better at training on an unstable surface.

The issue with this?

We don’t live on an unstable surface. We spend 99.9% of our time on stable ground, whether talking a sporting situation or just in day-to-day life.

The improvements in strength we see if training on an unstable surface don’t actually carry over to stable surface movements. Therefore we do not see the associated improvements in speed and power that come with improved strength.

In fact, they won’t even improve our ability to maintain stability on the ground, as the neural coordination required for even the same movement on the alternate (stable and unstable) surfaces differ too much!

In fact, stable surface training has shown to produce superior improvements in athletic performance measures in comparison to unstable surface training (1).

This is likely the same for day to day activities such as walking up stairs and standing from sitting.

We cannot train to our full capacity when on an unstable surface.

So the main reason we lift weights is to increase our strength and power, and develop muscle mass, right?

Well when we train on an unstable surface, our force production capacity is limited, as we spend so much neuromuscular effort to maintain stability. If we cannot produce maximal force, we are limiting our ability to both increase strength and power, and also build muscle, as the muscle is not placed under enough stress to elicit an adaptation response (2).


So to summarise

Unstable surfaces limit our ability to increase athletic performance and improve our capacity to undertake activities of daily living.

They also inhibit our ability to recruit muscle and produce force, therefore limiting strength and hypertrophy gainzzzzz.

But how do we improve stability?


Single leg work my friends, which is a topic for a future post.



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1.     Willardson, Jeffrey M. "The Effectiveness of Resistance Exercises Performed on Unstable Equipment." Strength & Conditioning Journal 26.5 (2004): 70-74.

2.     Anderson, Kenneth G., and David G. Behm. "Maintenance of EMG activity and loss of force output with instability." The Journal of Strength & Conditioning Research 18.3 (2004): 637-640.