Stability Balls, Wobbles and Bosu balls

Unstable surface training. What is it? What does it mean and what are the pros and cons?

Unstable surface training has become very popular in the gyms and with personal trainers everywhere. Everywhere you look you see people performing balancing acts worthy of Cirque de Soleil.

elephant on a ball

Unstable surface training may involve equipment such as wobble or balance boards, bosu balls, stability balls and 1/2 foam rollers. I am sure that you can pick up any magazine on fitness or even sport training and come across a picture of someone squatting on a stability ball or standing on a bosu doing shoulder presses, or bicep curls.

However, you need to ask is it safe, beneficial or getting you closer to your goals.

There are certain times during rehabilitation when using unstable surface training is necessary and recommended. This should be for individuals who have suffered an ankle or knee injury. Working on an unstable surface such as a wobble board has been shown to help restore proprioceptive and nervous system reaction deficits. In other words, it helps re connect the nervous system and the muscular system to regain proper movement patterns.

wobble board

Using unstable surface training in the hopes of increasing strength is not the most productive method. In a study done by Anderson and Behm, maximal isometric force output with the unstable chest press was significantly lower (59.6%) than in the stable condition. (1) What this means is that if you are going for strength gains, keep the exercise on a stable surface such as a bench.

Chest Press on a stability ball may be used to incorporate core stability work, but the weights used should be submaximal or higher rep range loads. Stability ball presses should never be used with maximum weights.

chest press on ball

What about core muscles and their activity during unstable surface training? A study by Nuzzo, McCaulley et all concluded that activity of the trunk muscles during squats and deadlifts is greater or equal to that which is produced during stability ball exercises. It would appear that stability ball exercises may not produce a sufficient stimulus for increasing muscular strength. (2)

iweight traiing

Everywhere you look in gyms and personal training studios, you will see a variety of equipment designed for unstable surface training. There are numerous tools in a trainers “toolbox”. All of them may be appropriate for certain clients at certain times. But, the question must be raised first – is it applicable to this situation? Is it beneficial to the clients’ needs or is the latest youtube creation.

squats on a ball

You must ask what the purpose is of standing on a stability ball or bosu ball performing a weight exercise?


The goal of the bicep curl for example is to build strength or mass or both. Standing on an unstable surface will limit the amount of weight that is able to be utilized without losing one’s balance. If you are attempting to solicit a neuromuscular response with balance and stability, there are more appropriate ways to do that. Single leg training for example.

Unstable surface training may have some merit with untrained individuals and in some rehabilitative situations, but as with any training tool their application must be carefully considered and applied.

Till next time,

(1) Anderson K. G. and Behm, D.G. Maintenance of EMG Activity and Loss of Force Output with instability. Journal of Strength and Conditioning Research, 2004 (18) 637-640

(2) Nuzzo, J.L., McCaulley, G.O., et al Trunk Muscle Activity During Stability Ball and Free Weight Exercises. Journal of Strength and Conditioning Research, January 2008. Volume 22, Issue 1, pp 95-102

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    4 Responses to “Stability Balls, Wobbles and Bosu balls”

    Sarah Rippel

    Great post, Narina!

    It’s crazy how there always seem to be fads in our profession: step aerobics, Nautilus, stability balls, Pilates, kettlebells, suspension training, HIIT, BOSU, etc. Many fads are legit but others fade away, and we are left to look back thinking “what the heck was all the excitement about?”

    Wobble boards were never my thing…I believe I last used one when I worked in a training studio, with a client who had ankle issues…had her do lateral and forward/backward rocking rehab-type work as active rest. Goal wasn’t even to balance on the board but to use it to guide the movement. At the time, I worked with a guy who seemed to love balance board training. He had everyone standing on a board while doing overhead presses. It seemed his “star” clients were those who could do a single-leg balance on the board while doing a 1-arm press.

    I do love lots of stability ball exercises but have gotten away from using it over the last couple of years.
    I have a BOSU for sale if anyone wants it! 🙂



    Sarah – how true! I use wobble boards very seldom. Usually with clients rehabbing ankle injuries, but like you not so much about balance but more the rocking motions. We use stability balls but not anywhere near as much as I have in the past. Not a lover of balance boards that much either. I have never invested in a bosu so sadly won’t take you up on your offer.


    Jon Kawamoto

    Thanks Narina,

    It’s crazy how people will create “functional” exercises on BOSUs and exercise balls – the safety issues are ridiculous!

    Jon Kawamoto from



    Jon – thank you for your comments. Yes, it never ceases to amaze me what you see trainers and clients alike doing on these ridiculous pieces of equipment. Hopefully these will fade by the wayside soon.

    What is scarey is that you still see some trainers using this crap and calling it functional or stability training.


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