In brief: Circuit weight training (CWT) can improve cardiorespiratory endurance, body composition, and strength, and sessions only take 25 to 30 minutes. Studies reviewed in this article showed that CWT increased aerobic capacity about 5%, compared with 15% to 25% in other aerobic exercise programs. Lean body mass increased 1 to 3.2 kg and fat decreased 0.8% to 2.9%. Strength improved 7% to 32%. Energy costs of CWT were similar to jogging at 5 mph. The authors conclude that improvements in strength and Vo2 max depend on work performed, not the equipment used. Although CWT does not develop high levels of aerobic fitness, it can help maintain fitness.