Strength training improves the steadiness of slow lengthening contractionsperformed by old adults

When old adults participate in a strength-training program with heavy loads , they experience an increase in muscle strength and an improvement in the steadiness of submaximal isometric contractions. The purpose of this study was to determine the effect of light- and heavy-load strength training on t he ability of old adults to perform steady submaximal isometric and anisome tric contractions. Thirty-two old adults (60-91 yr) participated in a 4-wk training program of a hand muscle. Both the light- and heavy-load groups in creased one-repetition maximum and maximal voluntary contraction (MVC) stre ngth and experienced similar improvements in the steadiness of the isometri c and shortening and lengthening contractions. The increase in MVC strength was greater for the heavy-load group and could not be explained by changes in muscle activation. Before training, the lengthening contractions were l ess steady than the shortening contractions with the lightest loads (10% MV C). After training, there was no difference in steadiness between the short ening and lengthening contractions, except with the lightest load. These im provements were associated with a reduced level of muscle activation, espec ially during the lengthening contractions.