The rate of perceived exertion is an easy and practical way to monitor the intensity of resistance exercise in a field setting. For middle-aged persons, weight-bearing exercise is safer than resistance training using weights. The purpose of this study was to investigate the effect of exercises using one's own body weight by measuring exercise intensity with the newly-developed perceived exertion Japanese scale (S-scale, on a 6-point scale) in middle-aged men. Twenty-five healthy men (age range, 40-70 years) were randomly and equally assigned to an exercise training intervention group (TG, n=13) or a control group (CG, n=12). TG members performed a structured exercise regimen consisting of group-based and home-based training using their own bodyweight, performing repetitions until they reached a perceived exertion intensity of 5 out of 6 (S-scale). Participants performed one set of each exercise, which included resistance training of the upper (push-up) and lower (squat) limbs and abdominal (sit-up) muscles, 3 times a week for 12 weeks. The outcome measures were body composition, abdominal girth, and blood pressure, as well as the 30-second chair-stand test (CS-30), vertical force in sit-to-stand movement from a chair, vertical jump (VJ), shoulder horizontal adduction (a test of muscle strength), 30-second sit-up test, leg muscle power using a bicycle ergometer, center of foot pressure (a static equilibrium function test), and chair sit-and-reach test. There were no incidents of injury or musculoskeletal damage due to the exercise program. At the baseline, each group was well matched in physical characteristics. After 12 weeks of intervention, we identified a statistically significant two-factor interaction between the exercise and control groups in the CS-30 (F=19.8, p<0.01) and VJ (F=34.4, p<0.01). These results suggest that weight-bearing exercises performed in conjunction with the newly-developed perceived exertion scale provide safe and effective resistance training for middle-aged men.
