What is the difference between aerobic and anaerobic fitness? A. Aerobic should be done at least thirty minutes a day, while anaerobic should be done no more than ten minutes a day. B. Aerobic refers to cardiorespiratory fitness, and anaerobic refers to muscular fitness. C. Aerobic is a type of exercise, and anaerobic is a type of stretching. D. Aerobic refers to muscular fitness, and anaerobic refers to cardiorespiratory fitness.