;s Abstracts): Older adults experience a marked decline in muscle mass (sarcopenia) and strength that can have a significant effect on the activities of daily living. As a countermeasure, a number of groups have shown that these individuals can experience a substantial increase in strength after participation in short-duration, strength training programs. Although most of these programs have involved heavy-load protocols, the investigators recent observations suggest that comparable gains in strength can be achieved with light loads if the participant focuses on exerting a steady force during each exercise. The investigators propose to test the hypothesis that older adults can increase muscle strength and achieve functional benefits with a strength-training program based on the use of steady contractions to lift light loads.
The specific aims will be: (1) to compare the effects of training load on the changes in muscle strength; (2) to assess the functional consequences of the training-induced increase in muscle strength; and (3) to characterize the types of neural adaptations that underlie the increase in strength.
These aims will be examined by recruiting older adults (65-80 years) to participate in a 16-week strength-training program. The predictor variables will be muscle group (knee-extensor or hand-forearm muscles), training load (30 or 80% of maximum), and degree of control (regular or steady muscle contractions). The outcome variables will be muscle strength, performance on functional tests, and the adaptations underlying the increase in strength. The investigators expect to find that older adults will be able to increase muscle strength in a program that uses light training and steady muscle contractions and that such a program will have a greater transfer to functional activities. This finding will underscore the critical role of neural adaptations in the strength gains experienced by older adults with short-duration training and will provide the foundation for an alternative therapeutic strategy for strengthening exercises in this population.
