What Is the Relationship Between Physical Activity and Cardiorespiratory Fitness?
Cardiorespiratory fitness is a sensitive and useful measure of changes in response to physical activity. It demonstrates dose-response relations with overall exercise volume and also with each of the various components of exercise volume (intensity, frequency, duration, and longevity). It appears that one can acquire improvements in cardiorespiratory fitness in bouts as small as 10 minutes each, while holding volume constant. It is unclear whether there is a relation between the duration of exercise bouts and fitness responses, when total volume is held constant, especially for vigorous intensity exercise. Changes in fitness during exercise interventions correspond with changes in cardiovascular risk, but do not always correspond with changes in cardiovascular risk factors.
