Concentric and Eccentric Exercises

In my last blog post, I described the differences in concentric and eccentric muscle contractions. I would now like to relate these actions to strength training exercises. When performing any strengthening exercise, I feel both the concentric and the eccentric contraction should be included to provide the most efficiency and practical application to daily physical activity.

The concentric motion occurs when the muscle shortens under load, such as the deltoid muscles of the shoulder shortening as you lift a  weight overhead. The same muscles are then called upon to perform the work in the eccentric phase when the weight is lowered from overhead back to its starting (or resting) position. Other surrounding muscle groups are again being brought into play throughout the full range of motion to stabilize and protect the joint, and allow the deltoids to perform the prime movement. I feel it is more efficient to increase the duration of the eccentric phase of a movement to avoid acceleration and thus decrease the risk of injury. Also, science has show that the longer time a muscle is under tension, the greater strength gain is achieved.

All the activities of our daily lives, such as, taking the dishes out of the cupboards, lifting boxes up onto shelves, getting the groceries into and out of the car, all require both concentric and eccentric muscle contractions. Working a muscle throughout both these phases strengthens it and makes these tasks easier and more efficient to perform.