ABSTRACT
It is now well established that an adequate supply of muscle glycogen is required to maintain high intensity exercise performance. At exercise intensities ranging from 70 – 80% of maximal aerobic power ( https://www.w3.org/1998/Math/MathML"> V . 0 2 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203720035/4f171d74-2867-42d1-88ad-137858f57c23/content/inline-math_19_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> max), exhaustion of the exercising muscles will occur after approximately 90 min when the muscles' glycogen stores are almost totally depleted (Bergstrom et al., 1967). Published data reveal that the physiological demands of soccer approximate similar exercise intensities. Radiotelemetry has shown that during a soccer match a player's average heart rate is high and may frequently approach maximum (for review see Ekblom, 1986). The mean distance a player covers during a match is reported to range from 8.7–11.5 km (Ekblom, 1986). It is important to note that a total of almost 1 km may be covered in short intermittent sprints (Reilly and Thomas, 1976), because the rate of muscle glycogen utilization is known to increase greatly as the level of exercise intensity rises (Saltin and Karlsson, 1971).
