The Gas Transporting Systems: Limits and Modifications With Age and Training

The interplay of cardiovascular and cellular oxygen uptake determinants of aerobic performance and the system adaptations to training in different population samples are examined in order to describe the limitation. With VO2max, a central limitation following myocardial infarction and ageing is modified with training. Peripheral adaptations occur and stroke volume may be increased primarily through improved diastolic filling. In submaximal perturbations, control of the increase in O2 uptake at exercise onset (O2 kinetics) is most often under peripheral metabolic control, but in exceptions may also be limited by central factors. In young and old the peripheral machinery is matched to the growth (puberty) and loss (ageing) of muscle mass. Cardiac stroke volume capacity may adjust following the changes in muscle mass. Submaximal endurance is closely influenced by the anaerobic threshold (theta(an)) and peripheral factors of oxidative metabolism. Relative to VO2max, the theta(an) is low in children and high in older adults, perhaps reflecting a slow time course in full development and loss of peripheral adaptations. Remarkable increases in endurance performance are related to relatively small changes in the maximal capacity and the relative intensity of performance.