Glycogen reduction in non-exercising muscle depends on blood lactate concentration

Kohler, Götz ; Boutellier, Urs

In: European Journal of Applied Physiology, 2004, vol. 92, no. 4-5, p. 548-554

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    The purpose of this study was to determine for the first time by repeated non-invasive 13C-NMR spectrometry whether blood lactate concentration affects glycogen reduction in non-exercising muscle during prolonged (6h) physical exercise in healthy adult males. Such an effect would indirectly show that glycogenolysis independent of nervous activation occurs in non-exercising muscle. After an overnight fast, 12 subjects performed alternating one-leg cycle exercise and arm cranking exercise at an average work load of 106 (SD 26)W [63 (9)% maximum oxygen consumption for one-leg exercise] and 69 (13)W [61 (10)% maximum oxygen consumption for arm cranking exercise], respectively. During the 6-h exercise test, glycogen concentration of the non-exercising calf muscle decreased by 17 (7)% while the glycogen concentration in the exercising calf muscle decreased by 45 (8)%. In a resting control group (n=6), the glycogen concentration did not decrease significantly. The higher the exercise intensity and therefore blood lactate concentration, the smaller was the glycogen reduction in the non-exercising calf muscles. We conclude that during prolonged physical exercise glycogenolysis in non-exercising human muscles decreases as exercise intensity increase contrary to exercising muscles. This observation might be an indirect evidence for a non-exercise induced glycogenolysis in inactive muscles