A Comparison of Muscular Strength and Power Development in Unilateral and Bilateral Lower Body Exercises

The purpose of this study was to compare muscle strength and power development following training programs that involved unilateral and bilateral lower-body exercises. A randomized between-groups research design was used in which results from a pretest and posttest were compared across the unilateral and bilateral groups. Sled machine one repetition maximum (1-RM) testing was used as a measure of strength, and countermovement vertical jump (CMVJ) testing was used as a measure of absolute power. Total body bioelectrical impedance analysis testing was used to predict lean body mass in both the left and right legs. Six college-aged female students who were not physically active completed 12 exercise sessions over a four-week training period involving a variation of squats, sled machine pushes, a deadlift, and box step-ups utilizing one or both legs. The specific variation of exercises for each participant was determined by randomized placement into one of the two groups. Sets, repetitions, and loads were determined using percentages of individual 1-RM values that were associated with ACSM recommendations for strength and power development. There were no significant differences in the change in 1-RM values (p=0.18) between the two groups. There were no significant differences in the change in CMVJ values (p=0.15) between the two groups. This study demonstrates a lack of significant differences in muscular strength and power development using unilateral versus bilateral lower body exercises and suggests that other factors of exercise prescription, such as exercise intensity and frequency, may play a larger role in muscular adaptation than the use of one or both limbs.