Background and Objectives: Resistance training is considered the most effective intervention for increasing older people’s muscle mass and strength. We devised a self-administered training system (squat + balance training, sukubara®) that incorporates a new low-load exercise. This study hypothesizes that introducing sukubara® affects skeletal muscle mass and physical function positively, and we first conducted a preliminary verification in healthy non-elderly participants. Materials and Methods: This study’s participants were non-elderly healthy hospital personnel. Applicants were randomly assigned to two groups, a resistance training group that performed an exercise program (sukubara®) and a control group that did not, and they received a 12-week intervention. This study’s primary endpoint was change in skeletal muscle mass; the secondary endpoints were knee extension strength and one-leg standing time with eyes closed. Results: An analysis of Tthe 18 participants (10 in the resistance training group and 8 in the control group), who were 18 analyzed this study’s results was performed. The results of changes in variables between both groups during the intervention period were as follows: skeletal muscle mass, knee extension strength, and one-leg standing time were significantly improved or tended to be significantly higher in a resistance training group than in a control group. Conclusions: A self-administered training system (sukubara®) incorporating low-load exercise resulted in muscle hypertrophy and improvement in physical function.