ABSTRACT
During the years of growth and development, the respiratory gas exchange system of children is required to meet varying metabolic demands, as is the adult system. The exact cellular events and cardiorespiratory adjustments that affect this adaptation in children are, however, less well understood than the adult mechanisms. The short duration activity patterns typical of children’s play do suggest that the maturing metabolic system is capable of rapidly accommodating work of high intensity. Previous studies have investigated the response of children during the initial stage of exercise. Some suggest that the time course of oxygen uptake https://www.w3.org/1998/Math/MathML"> V ˙ O 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315025001/ca0a1b50-16e7-4532-9e85-fe2cd38f2327/content/inline-eqn570_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> at the onset of constant load work is similar for children and adults[1, 2]. Cooper and colleagues[3] also demonstrated no apparent difference in https://www.w3.org/1998/Math/MathML"> V ˙ O 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315025001/ca0a1b50-16e7-4532-9e85-fe2cd38f2327/content/inline-eqn571_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> at the onset of constant load work in prepubescent children compared to adolescents. In contrast, other investigators[4, 5] have reported a faster https://www.w3.org/1998/Math/MathML"> V ˙ O 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315025001/ca0a1b50-16e7-4532-9e85-fe2cd38f2327/content/inline-eqn572_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> response in children at the onset of maximal exercise when compared to adults. Macek and Vavra[4] have speculated that this observed difference between children and adults may mean that children have fewer available glycolytic enzymes, resulting in lower anaerobic capability, or that the rapid onset of aerobic adaptation makes an anaerobic response less critical.
