What is the American College of Sports Medicine's recommendation regarding frequency to increase cardiorespiratory fitness?

One to two days per week is insufficient to generate the training stimulus needed for meaningful cardiorespiratory adaptations.

Two to three days per week falls below ACSM's recommended minimum for optimizing cardiovascular fitness gains.

ACSM's position guidelines state that three to five days per week of moderate-to-vigorous aerobic activity produces significant improvements in VO2max and cardiorespiratory endurance. This range balances adequate training stimulus with sufficient recovery time. Fewer days do not provide enough overload, while more days increase injury and overtraining risk without proportional benefit.

Four to six days per week exceeds ACSM's standard recommendation and may elevate overtraining and injury risk in general populations.