Top 10 Research Questions Related to Youth Aerobic Fitness

Neil Armstrong

Aerobic fitness may be defined as the ability to deliver oxygen to the muscles and to utilize it to generate energy to support muscle activity during exercise. Maximal oxygen uptake (V_ O2 max), the highest rate at which oxygen can be consumed by the muscles during an exercise test to exhaustion, is widely recognized as the best single measure of aerobic fitness and has been the criterion measure of youth aerobic fitness for about 80 years. V_ O2 max (or later peak V_ O2) is the most comprehensively documented laboratory-determined variable in pediatric exercise physiology, but its assessment, interpretation, trainability, and relationship with other health-related variables during growth and maturation remain shrouded in controversy.

V_ O2 max limits the capacity to perform aerobic exercise, but it does not define all aspects of aerobic fitness. In everyday life, young people’s spontaneous play and participation in sport are more concerned with short duration, intermittent exercise, and rapid changes in exercise intensity. Under these conditions, V_ O2 max might be considered a variable of investigative convenience rather than the principal physiological variable underpinning exercise behavior, and it is the kinetics of pulmonary V_ O2 (pV_ O2) that best describe aerobic fitness. In contrast with studies of V_ O2 max, there are remarkably few investigations of young people’s pV_ O2 kinetic responses to step changes in exercise intensity. Studies of the trainability of youth pV_ O2 kinetic responses are even rarer, and current comprehension is primarily based on comparative analyses of youth athletes and nonathletes.

The present discussion recognizes that there are several other indicators of aerobic fitness, including blood lactate and ventilatory thresholds, exercise economy, and recovery pV_ O2 kinetics, but the focus herein is on V_ O2 max (or peak V_ O2) and pV_ O2 kinetics at the onset of exercise, arguably the two most pertinent markers of youth aerobic fitness. The objectives of this article are to outline current understanding, reveal controversies in assessment and interpretation, identify gaps in knowledge, raise 10 relevant research questions (see Table 1), and indicate avenues for future research in youth aerobic fitness. The focus is primarily on the aerobic fitness of normal, healthy children, and readers interested in other populations (e.g., athletic, clinical) are referred elsewhere for discussion (e.g., Armstrong & McManus, 2011; Armstrong & Van Mechelen, 2017; Bar-Or & Rowland, 2008).

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