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

• Published in: European journal of applied physiology 2004-08, Vol.92 (4-5), p.548-554
• Main Authors: Kohler, Götz, Boutellier, Urs
• Format: Article
• Language: English
• Subjects: Adult; Anaerobic Threshold - physiology; Blood Glucose - metabolism; Electromyography; Exercise - physiology; Exercise Test; Female; Glycogen - blood; Glycogen - metabolism; Humans; Lactic Acid - blood; Leg - physiology; Magnetic Resonance Spectroscopy; Male; Muscle, Skeletal - metabolism; Rest - physiology
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-004-1109-2

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 (6 h) 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.