We’ve all seen it, the personal trainer with the Vibram 5 finger shoes, standing on a bosu ball, balancing on one leg with his eyes closed while holding a kettlebell over his head…all in the name of “functional training.” The claim of these unstable guru’s was that performing typical movement patterns on unstable surfaces (airex pads, physio balls, indo boards, etc.) would challenge balance and proprioception while forcing muscles to work harder to stabilize the body. This would lead to quicker gains in strength, burn more calories, improve sports performance, cure cancer, and feed the poor. But is there any truth to these claims?
First let’s start by defining functional training. Functional training has become one of the most overused terms in the fitness world these days and is typically lip service from trainers who really have no understanding of sound strength & conditioning principles. Functional training, in my definition, is any training that translates directly into improved performance of the desired task. Therefore any exercise, movement skill, or workout routine can be functional, if applied to the right situation.
The main defense for unstable surface training is increased muscle activation, more commonly referring to the core musculature. This claim is purely FALSE. Many studies have been performed measuring muscle EMG activity during various movement patterns on the ground and on unstable surfaces (Core Board balance trainer). Not only did the results show no differences in muscle activation between stable and unstable surfaces, they showed significantly more activation on the stable surface when heavier external loads were introduced1. Therefore, all of the balance board and bosu ball squatting is doing less for your body then just adding a heavier load to the stable movement. Most people are actually hindering their gains because the unstable surface forces you to use a much lighter load than what your body can handle. Now there is no progressive overload and you will see performance grind to a halt or begin to decrease. You want to activate your core? Grab some heavy dumbbells and lunge walk across the room while staying vertical through the torso. That will provide more core activation and firing of stabilizer muscles than 100 bodyweight squats on airex pads ever could.
When transferring to daily activity, or “functional” training, there is absolutely no evidence to show that performing activities on unstable surfaces will improve performance when returning to a stable surface. In fact, it is quite the contrary. Very few activities exist in life, or in sport, that are regularly performed on an unstable surface (the few examples would be tight rope walking, surfing or water skiing, but we’ll get to those shortly). When you perform an activity on an unstable surface your body is forced into a compensatory pattern, typically withdrawing force application and tensing up, to prevent injuring yourself on this foreign surface. If your ability to express power is reduced below your typical output, you will be training your body to perform the movement slower and weaker than your current capabilities allow (think of trying to sprint on a trampoline). If trained consistently this would certainly translate into daily activities or sports performance, however the translation would be reduced speed and power and less ability to express force! The sad truth is that many of these personal trainers are actually decreasing performance, all for the sake of being functional.
The final piece of the unstable argument, and quite frankly an embarrassing topic in this field, is training for unstable sports. Surfing is one of the most common sports that I see trainers try to mimic in the weight room, and the results are just appalling. Surfing is performed on an unstable surface. A 5-10ft piece of foam and fiber glass, propelled at high speeds through a constantly changing unstable environment. Surf training is an embarrassing mix of jumping onto boxes topped with half bosu balls, mimicking paddling with prone battle rope movements, and swinging kettlebells while balancing on indo boards. Surf athletes need a well-balanced strength program using multiple stances, movement patterns, and planes of motion. No amount of bosu surfing will ever mimic exactly what they will see or feel like when flying down the face of a 15ft wave. It will not transfer into their ability to ride that wave. What will transfer is the strength, body control, and intra-muscular coordination developed in the weight room paired with the only thing that will actually improve their performance in the water…endless hours on the board.
When unstable surface training began, it was a way for physical therapists to reestablish proprioception and motor patterns in patients recovering from injury. Somewhere along the way it got lost into the hands of so called “functional” trainers, with no real understanding of foundational training principles. It has now spread like wildfire to gimmicky trainers and coaches around the world. Taking a protocol that was developed for rehabilitation of an injury and applying it to a population of healthy clients or athletes would be like taking the directions from a box of microwavable macaroni and cheese and using it to prepare a homemade lasagna. It just does not make any sense. Stick to the basics. Make people move better, get them stronger, and teach them how to express force. Stop with the gimmicks and the flashy deceptions of the con artist trainers and get back to what is proven to improve performance.
1. Yongming, L; Chunmei, C; Xiaoping, C. (2013). Similar electromyographic activities of lower limbs between squatting on a Reebok core board and ground. Journal of Strength & Conditioning Research. 27(5): 1349-1353.