Often in the training world, we see the addition of an unstable surface to make an exercise more "functional." But what is the real outcome when incorporating BOSU balls, Swiss balls, Airex pads, etc. when working with clients? Are we making clients stronger? Do they transfer energy more effectively and efficiently when they work in a state of instability? Are we truly making our programs more functional? What is stability versus balance?
Whether it's for sport performance or everyday life, function is key. When considering function, the continuum is endless: we must be able to transfer energy from the ground up (e.g., picking up a box), or to an implement we may be holding (e.g., a golf club) for a powerful swing.
Stability and balance are often mistakenly conflated as the same thing, or used interchangeably; however, they are different concepts in the strength and conditioning world. Here lies the debate: stability versus balance.
By definition, stability is "to become stable, firm, or to be resistant to disturbance of equilibrium." For example, a bridge must be stable to allow cars to safely travel its length. Alternatively, the definition of balance is "an even distribution of weight enabling someone or something to remain upright and steady," for example maintaining balance on a boat rocking back and forth.
Observe these 2 images:
The image on the left shows a well-balanced but unstable structure. The one on the right is a much less balanced but stable structure, which could withstand external forces without collapsing.
Further exploration of stability versus balance and how they differ in the training world is multifactorial. Balance has a place in the realm of health and wellness/rehabilitation. When programming for function, we must create an environment of stability to enhance strength and "practice" the skill of energy transference. Having a direct connection with the ground and using ground reaction forces will allow your client to hit a baseball harder, punch an opponent more powerfully or jump higher to grab a rebound. The forces must be able to transfer from the lower extremities through a rigid core and continue to the "exit'" point.
Creating an environment of "instability" with a BOSU ball or an Airex pad will simply allow your client to practice balance while causing dissociation among the joints of the body. When there is dissociation of joints within the lower extremities, energy transference will be negatively affected from joint to joint, then through the core to the exit point. A 2009 study revealed no significant advantages with respect to core activation when using the BOSU balance trainer. Furthermore, ground reaction forces will be dispersed (lost) through the unstable device, minimizing the return of energy back to the body.
A 2002 study demonstrated that unstable devices account for 44% less muscle activity and 70% less muscle force output than stable surfaces. To practically apply these findings, perform a max squat strength test (3RM or 5RM) on 2 Airex pads or any unstable surface, then do the same squat test without the unstable surface and compare your final numbers.
What is the take-home message from this? Program for functionality. Make your program functional by creating a stronger, more stable person who is able to withstand forces from the external environment.
Perturbation—"deviation of a system, moving object, or process from its regular or normal state of path, caused by an outside influence"—can be used to accomplish this. Perturbation exercises are designed to be unpredictable and to elicit reactivity responses from the client; just as required in game scenarios. A trainer or partner can apply unpredictable forces to an athlete, for example by throwing balls at them or using a reaction stick to elicit maximum core stabilization, reactivity and force generation.
Watch the video above to see three exercises demonstrating these principles.
Photo Credit: Getty Images // Thinkstock