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Q: I play basketball on weekends and I want to make sure that I don't twist my ankles. Someone told me I should do exercises on wobble boards and unstable surfaces. I noticed that trainers at FIT don't often prescribe exercises on these wobble boards and unstable surfaces. Why?
A: Wobble boards and other "unstable" equipement have their places in a rehabilitation program, and may be useful for the extremely deconditioned. However, for the average, uninjured person, many other exercise techniques are more useful and efficient. But to explain, let's review the scientific literature so that we can gain the appreciation for the effectiveness of traditional strength exercises and to understand our reason for not over-emphasizing the trendy stability-ball and wobble board training commonly seen in the fitness and sport-training industries.
Foot strike and mobility are dependent on several factors that include the feedforward mechanism, muscle stiffness, body and joint positions, and magnitude of foot contact. In walking, running and landing from a jump, the muscles of the legs activate prior to contact. This causes muscle stiffness and allows the limbs (ankles) to act as springs -- this increases mechanical economy and contributes to continual movement.
When discussing ankle stability within a dynamic situation such as a basketball game, it is a useless conversation if we disregard the contribution of the other joints (knees, hips, back, arms, etc). These other joints help attenuate impact forces away from the ankles (or any one particular joint), but they must be aligned within the proper biomechanical parameters and they must act at a specific instant. This process is often a result of the "feedforward mechanism."
Feedforward, in the context of foot strike, contributes to how the body strategically aligns itself prior to foot contact, especially if there are obstacles in the path (ditches, holes, cones, another player's foot, etc.).
Training on the wobble board or foam roller targets primarily the feedback mechanism, and neglects the feedforward. Feedback is essentially a series of proprioceptive reflexes, triggering motor adjustments. Research shows that, AT BEST, the genetically-gifted, well-trained person can make 3 motor adjustments per second -- that's an average of one adjustment for every 0.3 seconds. Now here's the ticker: foot contact during normal running is less than 0.2 seconds, barely time for even one adjustment to occur. This fact has been thought to partially explain the muscular stiffness that occurs in the lower leg prior to and throughout footstrike (a temporal pattern). This stiffness occurs to stabilize the joint during contact and to act as springs to absorb and release forces. The foot doesn't simply stay relaxed at foot contact and then wait for feedback to tell it how to adjust. You'd break your ankle. In other words, in game situations, the force of each foot strike is often abrupt, large in magnitude or high in impulse, and too quick for adjustments. The lower leg must activate prior to contact and stay stiff for protection and to act like springs. Also, instability training does not increase the speed of reflex -- reaction speed is genetic.
According to some literature, *feedforward* is an important implication to motor strategies for injury prevention. If someone attempts a lay-up and in the process and "subconsciously" caught glimpse of the "area" on which he'll land, his body will automatically adjust to align itself and all its joints in the optimal position for the safest landing mechanics -- this is mostly a subconscious process so that he can concentrate on the primary task: putting the ball through the hoop. But if he didn't "see" and "subconsciously record" this landing area or another player's foot waiting at the landing area, the feedforward mechanism is thought to not be triggered and the body may not align itself and all its joints for a safe landing. This is often how athletic injuries occur, sometimes to even the best or most conditioned athletes (eh-hem... Jimmy).
You're either gonna get hurt, or you don't. The instant of injury is extremely fast, and intervention of the feedback mechanism might not be quick enough. So train on the wobble board all you want, but don't expect increased injury prevention over that of plyometrics, Olympic-style lifts, heavy resistance training. In fact, as far as current evidence shows, don't expect training on wobble boards to come even close to traditional training and conditioning.
Why then do we participate in strength and conditioning for athletes if they are "either gonna get hurt or they don't"? Because, in addition to performance enhancement, the more conditioned athletes are likely to delay fatigue, preserve mental sharpness, and make less technical mistakes. Further, the increased structural strengths in bones, connective tissues, and muscles may maximize tensile, compressive, and shearing tolerances for the mechanical stress placed on the body during sports.
Yet why do we still see injuries in even the most conditioned athletes? Sometimes the mechanical stress surpasses the structural strength of the body. Sometimes the stress is applied at a faster rate than the muscle's ability to contract and protect. Or sometimes the muscles don't relax in time to absorb the force. There are many factors. The mechanisms of injury are many. Although strength can decrease the risk of injury, it alone does not eliminate injuries, and as coaches, trainers, athletes and people who participate in fast-action sports it's important to know why. — Johnny Nguyen
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