This study examined the effects of a 6-month circuit gym workout on muscle and fat cross-sectional area (CSA) and muscle strength in middle-aged and older women. The participants were 49 women without severe metabolic disease, exercise limitation, or exercise habits. They were randomly assigned to two groups, circuit gym using group (CRT: n = 25) and walking group (WALK: n = 24). Both groups followed the exercise program for 6 months. Thigh and abdominal CSA before and after the program were measured using magnetic resonance imaging. Moreover, knee extensor/flexor and hip flexor strength were measured using a dynamometer. After completion of the exercise program, CSA of the psoas major muscle and isokinetic knee and hip flexion strength significantly increased in the CRT group compared with the WALK group (CSA: 7.1% vs 1.4% respectively; isokinetic strength: 7.5% vs −4.3% (knee), 23.6% vs 2.2% (hip), respectively). In addition, subcutaneous adipose tissue of the thigh in the CRT group significantly decreased compared with that in the WALK group (−6.5% vs −1.8%, respectively). These results imply that in middle-aged and older women, the use of circuit gym leads to a more effective increase in CSA of the psoas major muscle, decrease in thigh subcutaneous adipose tissue, and increase in knee and hip flexor strength compared with brisk walking.
