Weight Training Specificity
Concentric and Eccentric Muscle Contractions
When designing a weight training program, the athlete or coach must always ask themselves what purpose their training program will serve. If the athlete's goal is to increase muscular strength, their program will be different than if they are training to increase muscular size. Many trainees and coaches think that when training for either muscular size or strength, the only variables that will vary are the number of sets and repetitions performed. Another factor that needs to be emphasized is the types of contraction emphasized when performing weight lifting exercises. When lifting weights, most trainees pay no attention to whether or not the exercise they are performing or the way they are training emphasizes either concentric or eccentric muscular contractions. Concentric muscular contractions occur when the muscle being exercised is shortening. Eccentric contractions occur when the muscle being exercised is being lengthened. Recent studies have shown that the type of contraction performed plays an important role in muscle size and strength improvements.
Studies have shown that exercises that only involve concentric contractions produce the same improvements in muscular strength as exercises that involve both concentric and eccentric contractions. This same study also showed that exercises that involve both concentric and eccentric contractions cause greater improvements in muscle size that exercises that only involve concentric contractions. Therefore, when designing a training program, be sure to consider what the goals of the program are and choose exercises as well as repetition tempos that emphasize the appropriate muscular contractions.
One way to emphasize either eccentric or concentric contractions is to vary the rate of each repetition performed. When training primarily for muscular strength, athletes can place a greater emphasis on concentric contractions by decreasing the amount of time spent performing the eccentric portion of the repetition. When muscular size is the emphasis of the training program, eccentric contractions can be emphasized by increasing the amount of time spent during the eccentric phase of the repetition.
Negatives are another way to emphasize eccentric contractions. To perform a negative repetition, a weight that is greater than what could normally be performed in a concentric/eccentric fashion is used. Using attentive spotters, the trainee lowers the weight resisting the weight as it is lowered. Once the eccentric contraction is completed, the spotters help to raise the weight back to its starting position. Negatives are often performed at the end of a set when no more concentric/eccentric contractions can be performed. Use negatives sparingly. The increased amount of trauma incurred by this type of exercise increases recovery time and increases the risk of injury or overtraining.
O’Hagan FT; Sale DG; MacDougall JD; Garner SH. Comparative effectiveness of accommodating and weight resistance training modes. Medicine and Science in Sports and Exercise, 1995 27:8, 1210.
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