How much improvement in aerobic capacity can a person typically expect to experience, and how long does it take?
Increases in cardiorespiratory fitness with exercise training generally show a positive correlation to the frequency, intensity, and duration of exercise. The amount of improvement in aerobic capacity (i.e., VO2 max) that can be expected from training is very individualized and is inversely related to each individual’s level of fitness. In other words, the more fit an individual is the smaller the degree of improvement in VO2 max associated with training. For example, an untrained individual may experience approximately a 25 percent increase in VO2 max after roughly 8 to 12 weeks of conditioning. A trained individual, on the other hand, may experience only a five percent improvement over the same period of time.
