Wobble Boards, Bosu Balls, or Foam: What's The Difference?
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See the core strength and stability category for more articles about training the core.

By Eric Troy, Ground Up Strength

You've probably seen a wobble board before. They are these round discs with a ball or disc underneath them. Bosu balls are similar but they are more like a half swiss ball with a platform attached. Figure 3 below shows a boy jumping from bosu ball to bosu ball using the "ball" side. These can also be turned over on a hard surface so that the ball is a pivot. People use this method for pushups, for instance.

They are used for rehabilitating ankle injuries. The idea behind it is to retrain the proprioceptive mechanisms that can be damaged when a joint is injured. Basically, your body has sensory organs called proprioceptors which relay information about the body's position to the brain. In the case of the actual joints, information about a joints angle relative to the rest of the body is monitored this way. Without this you'd be in big trouble. If your ankle, for instance is turning under that needs to be quickly and automatically corrected. When the ankle is injured this proprioceptive sense can be damaged and this is one thing that leads to repeated ankle sprains.

Wobble boards can help to retrain this proprioceptive sense. And it works. It's a good thing and is perfectly suitable to a rehabilitative setting. But that is where it ends.

However, many trainers have taken it out of the rehabilitation setting and applied it to general training. You see people doing all sorts of things on unstable surfaces. Like barbell squats on wobble boards, bosu balls. As if doing weighted exercises with these isn't enough we now have people doing barbell back squats standing on top of Swiss balls like in the image below right.

It should be needless to say, but this is a dangerous and ill-conceived practice and, if you don't get injured, it is more likely to worsen your performance than improve it. Basically this is mistaking balance for stability. They think that if you are standing on a bosu ball or wobble board you are training stability but in fact you are simply learning how to balance on a bosu ball or wobble board. If, when you are standing on solid ground you have no problem with a squat, for instance, meaning that you have the stability to squat a loaded barbell then putting you and the barbell on top of a bosu ball does not suddenly prove you unstable. It means that your foundation is unstable and you will have a harder time resisting changes to your precarious equilibrium. Perching yourself on a bosu ball is good if you are training to be a ninja. Not so good if you are training the squat.

Balance is your ability to control your equilibrium. If you are standing up then you are in equilibrium, for example. Stability is your ability to resist changes in equilibrium. If I come and push you your ability to remain upright is an example of stability.

Figure 1: Wobble Board



Balance is a specific skill. That means is is specific to the surface it is developed on. The way a tightrope walker learns to balance on a tightrope is to walk on a tightrope. Having mastered the tightrope will not make him better able to be a linebacker.

Now, Louie Simmons and even the Diesel Crew are touting similar practices. Except it's using a foam pad. You are supposed to walk on a foam pad or do bulgarian split squats, or step-ups off one.

To be fair Jim Smith, author of Combat Core and a very innovative strength coach, intends the foam use for rehabilitative and activation purposes. However, I would want to know exactly what injuries and who it was intended for before I engaged in such practices. And that would entail an actual injury analysis by a qualified therapist.

Perhaps the current trend toward bridging the world of therapy with the world of strength and conditioning coaching has gone a bit too far. When strength coaches start "minding" therapist, who typically know very little about strength training and therapists start to portray themselves as the future of strength and conditioning, things are getting strange. Whatever the case, slapping a rehab label on something intended for a general audience is not something I can agree with.

Unstable surface training was meant for rehabilitative purposes and as such was employed in a specific way toward specific injuries.

I could be wrong but I just don't see a difference between doing things on a wobble board and on a piece of foam. Besides the obvious difference of course. I see them both as unstable. I don't expect that having a foot planted on a piece of foam or walking on foam will actually impact performance on a hard piece of ground. And I would expect many people to turn an ankle stepping down to one doing step ups. Or trying to balance on one doing split squats.

Another supposed benefit is inhibiting the "push-off" during step-ups. Well, there is no push-off in step-ups. If you are pushing off then you have not gotten step-ups down. There is one working leg. Side-stepping things and using a piece of foam to inhibit the push-off will just keep you from learning how to control the movement and use the working leg's strength and your own stability to master the movement and get stronger. I do step-ups with a loaded barbell on my back. I don't pushoff. I control the descent. I do not allow my back leg to crash down to the floor and only come down to the ball of my foot. This is how I do it and this is how I teach trainees to do it. If they push-off they get a lecture.

As a matter of fact I have noticed that many people have just as much trouble getting stable doing a bulgarian split squat as they do just moving it up and down. They need to start with a static split squat just on the ground and even that is a challenge. If there is any place for the foam..it is a advanced place. If you can't balance enough to do a split squat I doubt very much that doing it on foam will train that balance faster.

Most people that I have trained lack stability in a stable environment. The last thing they should be doing is training in an unstable one. It violates specificity. To me, unstable is unstable. People used to think that doing wind sprints on the beach would make you run faster. More likely it will screw up your running mechanics.

Of course I've heard the time honored pseudo-scientific argument about humans having 'evolved' to run on sand and grass. The point is, however, that the surface you are moving on makes all the difference. Sprinters, for instance, can sometimes encounter serious difficulties between one running surface and another even though both surfaces could be considered hard surfaces. Indoor volleyball players would certainly take some time getting used to beach volleyball. How would beach volleyball players do if they suddenly had to switch to a hard surface? Likely it would at least "feel weird". But heck, even the balls are different, the approach distances are different…everything is different reflecting the two different realities. All the things that you have to change to be successful on the sand are not going to make you better on the court because in many ways they are just too different. I would think this is a fundamental truth that can be generalized to some extent.

bosu ball jumps

Figure 3: Bosu Ball Jumps? Wouldn't have my son do this.

Vibrational training is the new big thing set to overshadow wobble boards and stant blades. This is where training takes place on some type of vibrating platform. All sorts of science going on by men in lab coats concerning that. I see this as well as being just another unstable surface, as do many others. As they say the jury is out and I have a feeling they will be out for quite a while. You can read Cardinale and Bosco's review of the literature here in this Pdf. And here where vibrations seems to have improved counter-movement jump performance in women but worsened it in men. In any case the supposed improvement seem to be temporary in nature.

I'm no expert though, so I'd suggest you dive deeper into the research.

Since this article has been up Jim Smith expressed his concern that I am misrepresenting his views. He points out that the idea of the exercises on foam rolls is rehabilitation and activation, and I included a paragraph above to that effect. This is outlined in his article. I personally don't see it and I don't feel that I put any words in Mr. Smith's mouth in this article but in fairness I wanted to include Jim's explanation for this. For example, doing Bulgarian split squats with the foot on foam is for glute activation and knee stability, among others.


This page created 18 Apr 2009 16:00
Last updated 29 Jun 2014 21:19

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