Aerobic fitness and its relationship to sport, exercise training and habitual physical activity during youth

Abstract

Aim: To analyse aerobic fitness and its relationship with sport participation, exercise training and habitual physical activity (HPA) during youth. Methods: Studies were located through computer searches of Medline, SPORT Discus and personal databases. Systematic reviews of time trends in aerobic fitness/performance, and exercise training and peak oxygen uptake (peak VO 2) are reported. Results: Peak VO 2 increases with age and maturation. Boys' peak VO 2 is higher than girls'. Despite data showing a decrease in performance test estimates of aerobic fitness there is no compelling evidence to suggest that young people have low levels of peak VO 2 or that it is declining over time. The primary time constant of the VO 2 kinetics response to moderate and heavy intensity exercise slows with age and the VO 2 kinetics response to heavy intensity exercise is faster in boys. There is a negative correlation between lactate threshold as a percentage of peak VO 2 and age but differences related to maturation or sex remain to be proven. Young athletes have higher peak VO 2, a faster primary time constant and accumulate less blood lactate at the same relative exercise intensity than their untrained peers. Young people can increase their peak VO 2 through exercise training but a meaningful relationship between aerobic fitness and HPA has not been demonstrated. Conclusions: During youth the responses of the components of aerobic fitness vary in relation to age, maturation and sex. Exercise training will enhance aerobic fitness but a relationship between young people's current HPA and aerobic fitness remains to be proven.