ABSTRACT
Maximal 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-eqn155_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> max) identifies the greatest rate at which the metabolic machinery of skeletal muscle cells can utilize oxygen in the provision of energy for locomotion. At submaximal levels of exercise 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-eqn156_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> is established by the aerobic demands of muscle contraction. Current evidence suggests, however, that the upper limit of 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-eqn157_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> during progressively intense exercise (i.e. 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-eqn158_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> max) is defined by oxygen delivery rather than muscle uptake. That is, it appears that factors such as maximal cardiac output, oxygen carrying capacity of the blood (i.e. haemoglobin concentration), and vascular supply to muscles are responsible for the “ceiling” of aerobic metabolic expenditure during exercise.
