Last post I discussed the proper implementation of functional training for varied populations. In summary, functional training is whatever training allows you to optimally carry out all of the tasks you encounter in a given day. As promised I am going to take some time to analyze the most commonly used and misused functional training modalities and see how effective they actually are and when to apply them to training yourself or others.
Today we will be taking a look at the use of unstable surface training. This includes equipment such as bosu balls, wobble boards, airex pads, gymnast rings or simply adjusting one’s foot or hand position to alter stability in a given exercise. I will start by addressing what these training techniques claim to be effective for.
The general thoughts behind traditional unstable surface training are as follows:
- improving balance on an unstable surface will make balancing on a stable surface easy
- causing the core muculature to fire more during an exercise must improve core strength and therefore create more stability in my other activities 
If our goal in training is to improve balance and stability maybe we should define these terms.
Balance – ability to maintain equilibrium in a static or dynamic setting
Stability – the body’s ability to resist acceleration
Balance and stability can both be demonstrated in static and dynamic postures. A static balance test might be the ability to stand on one foot and dynamic balance the ability to land on one foot. Static stability is the ability to hold very still such as in a plank, whereas dynamic stability is seen when carrying a lot of bags of groceries and having to maintain a neutral spine while opening the door with your opposite hand. Dynamic balance and stability are much more applicable to real life scenarios.
So the big question is does unstable surface training (UST) provide an increased ability to perform dynamic balance and stability tasks in real life? In short, the answer is no, but let’s delve a little further into some of the research.
UST causes very different muscle recruitment than traditional ground based training. This is the primary reason for its ineffectiveness. Every action has an agonist and an antagonist movement. The agonist is the prime mover and the antagonist is the opposing muscle, or the decelerator of the movement. When performing on unstable surfaces the antagonist is recruited to a far greater degree. The unstable surface is interpreted as a threat by your body and antagonist muscles are activated as a sort of braking system. Your body knows that if you go full throttle while you are standing on a wobbly surface you are likely to get hurt. Using UST in as little as 2-5% of your training volume can alter muscle recruitment patterns in all activities, leading to decreased force output in other exercises.
Balance on an unstable surface is a very skill specific task and recruits muscles very differently than balance on a stable surface (you know, the type of surface that we walk, run and play on here on earth). Even ice hockey players who operate on an unstable surface in their sport have been shown to receive no additional benefit from unstable surface training compared to traditional strength training without unstable surface training.
Balance is very skill specific. John Wall has tremendous dynamic balance on a basketball court. On the mound...not so much
In life and in sport instability often arises from insult higher up the kinetic chain which the trunk and hips have to respond to. This is why there is some value in UST for the upper extremity. Take the grocery carrying example from before. I am not unstable because the ground was moving beneath me. I was unstable because I was attempting to move while asymmetrically loaded and dealing with a shifting load in my upper extremity. A great way to mimic this real life scenario is with a single arm kettlebell carry.
Or a plank march
We can see a similar story with balance. Dynamic balance challenges in life arise when the body is suddenly forced to shift positions and express force from varied foot positions. Simple locomotive warmup drills similar to what you might see from a track and field athlete are excellent for training dynamic balance. That can eventually be progressed to a more strength based lunge matrix routine and eventually a heavy unilateral exercise selection.
For athletes interested in increasing maximal force output (ie. All healthy athletes) unstable surface training may be detrimental to your performance. The more frequently you do these type of exercises the more the body becomes conditioned to recruit the muscles in this pattern. Bad news for people that want to be strong and fast.
This article would not be complete without addressing the issue of UST in rehabilitation settings. Unstable surface training for the lower body has been shown to decrease the incidence of re-injury in rehabbing athletes. However uninjured athletes do not decrease their likelihood of injury by incorporating this type of training.
I am not here to tell you not to utilize UST in your own programming. I just hope that you can now use it in a way that translates to the needs of you or your clients. Unstable surface training has a use for healthy athletes. Standing on a Bosu ball does not.
 Research has shown increased muscle recruitment of the rectus abdominus during many unstable surface training exercises. The problem with this research, and much research built around EMG activity is that performance is not based solely on muscle force output, but on a coordinated effort of a series of muscles that fire in a specific sequence for optimal performance