Should You Strength Train On Unstable Surfaces?

On the BOSU ball

A patient come to our clinic this week injured after lifting weights on an unstable surface. The studio he went to had them do chest presses and flys with a glute bridge on a BOSU ball (knees bent, buttocks up and feet resting on BOSU ball). 

Indo board

I often use the BOSU ball, wobble board and/or  Indoboard (much later on - see end of article) when my patients require proprioceptive training to prep them before they return to sport. Also for those if they have lots of metalwork (pictured below) in the ankle after a fracture. I find that challenging my patients on unstable surfaces may enable them to rehab faster compared to stable surfaces when it is safe to do so.

Check out all the metal work in the leg

Other than working on their balance and proprioception (joint position sense), I get them to step on and off, lunge sideways, forward, backwards and sideways so they will be ready when the terrain that they are on are cambered or cobblestones (especially overseas).

However, I never use them while doing strength training. Turns out there is some research supporting that. I came across the following article to investigate if there are benefits or cross over effects of strength training on an unstable surface.

The following study evaluated subjects undergoing stable and unstable resistance training for muscle power. The subjects were randomly assigned into 2 groups. Each group performed resistance exercises under stable or unstable conditions 3 times a week for 8 weeks. 

Before and after 4 and 8 weeks of the training program, the subjects underwent squats and chest presses on either a stable surface or BOSU/ Swiss ball with increasing weights of up to 85 percent 1RM (rep max). 

There were significant improvements of mean power during chest presses on a Swiss ball at weights up to 60.7 percent 1RM after 4 and 8 weeks of raining on an unstable surface. Mean power also increased significantly during squats on a BOSU ball at weights up to 48.1 percent for 1RM after 4 weeks but not after 8 weeks of training on an unstable surface.

There were no significant changes in mean power during bench presses and squats on a stable surface after the same training. We do know from previous studies (Zemkova et al, 2014) that lower pre training values of power during resistance exercises on unstable surfaces are expected when compared to stable surfaces, especially at higher weights.

The researchers concluded that there is no cross over effect while weight training on unstable surfaces. Training has to be specific, if you want to get really strong and increase your 1RM max, you do not train on unstable surfaces since you cannot lift as heavy compared to on a stable surface.

Now you know, so you do not get hurt while trying something different that your gym suggests you do.

References

Zemkova E, Jelen M, Cepkova A et al (2021).There Is No Cross Effect Of Unstable Resistance Training On Power Produced During Stable Conditions. Appl Sci. 11(8): 3401. DOI: 10.3390/app11083401

Zemkova E, Jelen M, Kovacikva Z et al (2014). Weight Lifted And Countermovement Potentiation Of Power In The Concentric Phase Of Unstable And Traditional Resistance Exercises. J Appl Biomech 30: 213-220. DOI:10.1123/jab.2012-0229.

How's that for balance?