Comparison of Strength Gains in Untrained College-Age Females Using Free Weights and Freemotion Machines

Resistance training has become a preferred method for developing muscular strength among various populations. A variety of resistance training modes are available, but there are mixed outcomes regarding strength development among barbells, dumbbells, and weight machines. The purpose of this study was to investigate the differences in strength improvements between dumbbell and FreeMotion machine training. Twenty college-age females were randomly assigned into dumbbell or FreeMotion groups, but only 8 in the dumbbell group completed. Both groups followed a nearly identical progressive strength training program on each of their training modes for 8 weeks. Participants were tested on their one-repetition max (1-RM) on a barbell bench press and barbell back squat before and after the intervention program. A repeated measures ANOVA analysis compared 1-RM changes between groups, and effect sizes were calculated. Significant increases in strength improvements (p < 0.001) were observed for the dumbbell and FreeMotion groups, with moderate effect size for the 1-RM barbell bench press (d = 0.56) and a moderate to large effect size for the 1-RM barbell back squat (d = 0.73). There was no Group × Time interaction for the strength tests (p = 0.201 for 1-RM barbell bench press and p = 0.816 for the 1-RM barbell back squat, respectively). Dumbbells and FreeMotion machines were equally effective in improving strength in college-age females. The findings add to the literature on FreeMotion machines and benefit novice resistance trainers, physical educators, and fitness professionals. The study should be replicated with additional populations.