Deceleration in Sport
April 21, 2013
Most often when people talk about preparing for a sport, they all look at numbers. How fast can I run? How much weight can I lift? How hard do I throw the ball? Those are all valid questions when we’re talking about sports performance. They are important to note if you are being scouted to play in college or professionally. But a common thing I see left out of training is: how do we stop?
Earlier today I listened to a podcast of an interview with Jerry Shreck, the head strength and conditioning coach at Bucknell University. The discussion’s topic revolved around ACL prevention. I also purchased his “Deceleration Training to Prevent ACL Tears” program and will be digesting that information in the near future. But today we’re going to talk more general terms. I want to talk about all of the eccentric activity that takes place in sports. Why don’t we do a better job of training for that?
First of all, let’s discuss eccentric training. What is it? Eccentric muscle contractions occur when a muscle is working while it lengthens. For example, in a bicep curl the biceps muscle is working concentrically to pull the wrist closer to the shoulder causing a shortening of the biceps muscle fibers. The triceps are doing the opposite in that they are contracting eccentrically as the muscle lengthens which helps to stabilize the elbow joint through the process. When it reverses and the wrist moves away from the shoulder, the biceps are now the muscles working in an eccentric fashion to control the descent.
Training eccentrically has been shown to improve muscle strength so it is important that we work eccentrically in our training as well as contrentically. This will build stronger muscles which will benefit us down the road!
So, let’s go back now to deceleration in sports. I mentioned one example of eccentric activity earlier, but there is a lot of it that happens throughout the course of sporting events. Let’s think about that baseball pitcher trying to throw the ball 90mph. His arm may be able to get up to that speed, but what about stopping? If it’s not a controlled movement then injury will occur. That’s where the musculature of the rotator cuff comes in play. The rotator cuff muscles, namely the infraspinatus and teres minor, are responsible for this deceleration. They will work eccentrically to control the arm through its movement. If they are weak, the humeral head will not stay in place properly and tearing of the muscle or tendons may occur.
Another example is our ACL injury that everybody likes to talk about. So many times an ACL injury is caused by a rapid planting and cutting in which the body simply cannot control itself. One responsibility of the ACL is to control the anterior translation of the tibia on the femur; it needs the hamstrings and glutes to work eccentrically to control that translation as well.
Last example of deceleration and eccentric contractions is one that I’m continually looking at recently due to an abundance of injuries. That is the eccentric nature of the peroneal muscles. From a kinesiology standpoint, the role of the peroneals is to evert the foot. But in a functional viewpoint, the action is an eccentric contraction to control and limit inversion. Inversion is a common mechanism of injury for ankle sprains leading to injury of the lateral ligaments of the ankle. A side effect of ankle sprains can be the tearing of the retinaculum of the which can subsequently lead to chronic subluxation of the peroneal tendons. This can become irritating and/or painful and eventually lead to surgery to repair.
So I provided a few examples of common injuries that can occur when we are not properly prepared for eccentric movements in sport. We want to be able to go faster all the time, but stopping is an afterthought. We must consider stopping more often if we want to prevent athletic injuries.