Quadriceps strength training using two forms of bilateral exercise

The purpose of this study was to determine the effectiveness of quadriceps strength training in 15 women using bilateral constant resistance computerized exercise equipment that enabled only concentric contractions. To facilitate this investigation, data from an experimental control group (n = 14), using bilateral variable resistance exercise equipment which enables both concentric and eccentric muscle contractions, and a nonexercise control group (n = 17) were incorporated into the study design. Through a random selection process, subjects were assigned to one of three groups that participated in this 10-week study. Analysis, including univariate and multivariate statistical techniques, revealed no significant changes in strength between the two experimental groups. However, compared with the nonexercise group, there were significant increases in strength in the experimental exercise groups; yet, these increases were significant in both groups only on the right legs. In addition, the development of transient knee pain in two subjects engaged in both concentric and eccentric training required their removal from the study. This finding, in concert with previous experimental evidence of an association between eccentric exercise and the development of transient pain, must be integrated into future studies. Results suggest that further investigation is necessary to reveal the neurologic or biomechanical factors which may result in unequal training stimuli to the limbs with bilateral strength training on various types of equipment.