Posted March 12, 2012

Bosu? No Thanks, I Prefer to Get Results

A funny thing happens when you get a chance to teach a group of young and hopefully trainers in training. You get a chance to see what is the common thought processes among those who aren’t quite immersed in the fitness industry yet and have all the same preconceptions of the general public. You also get a chance to see what their trainers (if they’re working with any) might have them do and kinds of exercises they may be doing.

One of the big things I’m seeing is a really big use of unstable surfaces, such as the bosu ball, in the premise of helping promote core stability, weight loss or gaining muscles.

Now I’ll admit that I’ve used the bosu in the past to train clients, as well as other unstable devices, and I still will in certain situations depending on what is required and who is using it, but for the most part (meaning 95% of the time), I’ve stopped using any type of unstable surface training altogether in favour of heavy double leg or single leg movements that actually, you know, do something beneficial.

Unstable surfaces first gained use in the world of physiotherapy and rehab as a means of regaining lost proprioception following injury. By using a somewhat unstable surface, the participant had to get co-contraction of the muscles around the ankle, knee, hip and spine in order to maintain balance and not fall on their jug. As a result of this, they got muscle activity without having to take the injured joint through a range of motion and without placing a load on the injured area, while also working on making sure the tissues through the area synchronized their impulses to produce a strong and stable contraction over a prolonged period of time instead of just a single pulse or two.

Fitness took this and said “Hey, I could get some abz with that there thang!!” and proceeded to do all manner of biceps curls (with kettle bells no less) and squats with enough valgus collapse and knee dominance to make surgeons wring their hands in anticipation of the crush of business to come.

While the initial concepts being used in the rehab world were good for the right circumstances, like many cross-over attempts (Kobe Bryant as a rapper? Who couldn’t love that?!?), using unstable surfaces to get any benefit from people who have no injuries or neuromuscular impairment just doesn’t seem to stand up. It’s like using the foam roller on your IT band when your IT band isn’t tight, it gets you no where.

The funny thing is there’s been a huge crush of research in the past decade that has shown that using an unstable surface doesn’t actually increase core muscle activation anywhere, and performing exercises on it (like a chest press) has no impact on the scapular stabilizers at all. The Cybex Institute put out a really well-written position article in 2009 on it and showed a lot of the basis for moving away from unstable surfaces.

One tennet that makes me want to not use an unstable surface is simply because you can’t lift as much weight on them. Seriously, it’s not a pure ego standpoint and I’ll explain. If you’re on an unstable surface you’re spending much of your time trying to find your balance, which means you can’t use as much weight due to your lack of stability. This means the overall stress you can impart on your system is reduced, which means the demand on your prime and stabilizing muscles is reduced.

But isn’t the goal to challenge the small stabilizer muscles??

Okay listen. If you’re moving a Mack truck equivalent amount of weight on your back, you HAVE to use your stabilizer muscles or you run the risk of having your arms rip off your torso or having your knees resemble those of a praying mantis by the time the first rep is complete. If you’re lifting the equivalent of a cup of coffee while standing on a donkey with one foot and twirling a hula hoop with your left testicle, you’re not going to get the same level of stimulation out of your stabilizer muscles.

If you want to work your stabilizer muscles, hang on to some heavy-ass dumbbells and go for a walk.

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The basis for how much using a bosu sucks can come from math. Now before you go shutting down and thinking I’m going to get all calculus on you, I hate math with a passion when I’m trying to learn it, but it comes in stupidly handy when you’re trying to make a valid point. Let’s look at the basic formula for determining work:

Work = Force x Distance

If we can’t impart the same amount of force during a specific movement, the result is less work on the system, which decreases the overall impact of the exercise on features of adaptation like muscle micro tears (necessary for hypertrophy), caloric expenditure (necessary for weight loss), and endocrinological response to stress (necessary for continuously being a boss).

Let’s look at it another way. If we’re trying to move the same amount of force on an unstable surface versus on the ground, and we have to work harder to generate stability on the unstable surface, you have to slow the movements down. Using the formula for power:

Power = (Force x Distance) / Time

If it takes longer to do, it results in less power. This means speed development will be hindered as well as acceleration capacity. It’s long been known in the track and field world that the harder the surface the greater the velocity and the faster the rate of acceleration, so running on the softer field was typically only done by the slow kids who wanted to play soccer.

Well, isn’t it more functional to train on an unstable surface? Kind of like how skiing is on an unstable surface or how you have to respond in basketball or hockey??


First, no. Second. I haven’t played a single game of basketball that was played on a moving court. Sure, there was that one season that Slamball was around )which was AWESOME by the way), but when we play any kind of sport, the surface doesn’t really move all that much. The difference is that you’re moving your body over a surface that doesn’t change but may have varied slopes and angles to it. This means training on a surface that always alters itself doesn’t actually provide any type of functional training whatsoever, doesn’t it??

Instead, maybe move over a surface that has some difference in the coefficient of friction, or variability in its’ terrain. Sure, it may not be as portable as a flat sided dome, but portable don’t make functional baby. Some good examples of more functional devices would be something like a sideboard:

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or a Pro Fitter 3D trainer:

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Using unstable surfaces works more of the muscles of your ankle and feet, which makes it a functional exercise for keeping ankles strong for sports, right? Sorry, nope. If you’re standing on an unstable surface, your ankle joint isn’t changing position very much at all, and worse you’re not loading the ankle with any tangible velocity, acceleration, force, or anything that it would get exposed to during sports. This means the exercise makes you really good at maintaining a stable ankle in a fixed position, but doesn’t really train you to create stability outside of this range of motion, absorb acceleration or create acceleration, or become stable in any position outside of this static stance.

Does using unstable surfaces have merit? Absolutely, in individuals who have reduce proprioception through their lower leg, and are in a stage or rehabilitation where muscle activity without large degrees of movement are desired. In healthy individuals, not so much.

I’m more than happy to have people disagree with this thought process, but hopefully I’ve laid out some reasons as to why using unstable surfaces may not be that beneficial to training individuals who aren’t recovering from an injury. In the end, standing on one foot to do an exercise is typically more than enough challenge for people to see some real challenge, so using funny gadgets is more often than not a waste of resources, and lifting something heavy tends to produce better results in the “small stabilizer muscles” comparatively.


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