One Fitness Test Only. Valid for 6 months. An initial VO₂ Max test can clarify the precise target heart rates that will enable each individual to exercise more effectively, with less fatigue and fewer injuries. Periodic retesting provides motivating feedback as the fitness program progresses. Studies show that previously sedentary people training at 75% of aerobic power for 30 minutes, 3 times a week over 6 months increase VO₂ Max an average of 15-20%.