Glycogen Depletion Pattern in Human Muscle Fibres During Distance Running
Article first published online: 8 DEC 2008
© 1973 Scandinavian Physiological Society
Acta Physiologica Scandinavica
Volume 89, Issue 3, pages 374–383, November 1973
How to Cite
Costill, D. L., Gollnick, P. D., Jansson, E. D., Saltin, B. and Stein, E. M. (1973), Glycogen Depletion Pattern in Human Muscle Fibres During Distance Running. Acta Physiologica Scandinavica, 89: 374–383. doi: 10.1111/j.1748-1716.1973.tb05532.x
- Issue published online: 8 DEC 2008
- Article first published online: 8 DEC 2008
- Received 19 January 1973
Costill, D. L., P. D. Gollnick, E. D. Jansson, B. Saltin and E. M. STEIN. Glycogen depletion pattern in human muscle fibres during distance running. Acta physiol. scand. 1973. 89. 374–383.
Muscle biopsy and venous blood samples were taken from 9 subjects before and after a 30 km race. Additional measurements were made when 8 subjects ran 20.5 km of the course 2-3 weeks later. Information about total metabolism and the glycogen depletion pattern in the fibres of the thigh muscle during prolonged running has been obtained from these measurements. The average oxygen uptake and respiratory exchange ratio were 4.7 1×min-1 (83 % ot maximal oxygen uptake) and 0.90, respectively. An average intramuscular tryglyceride reduction of 2.2 mmoles×kg-1 (30 %) accounted for only part of the lipid combusted. Muscle glycogen declined 56 % (from 98 to 42 mmoles of glucose units × kg-1) during the race. Histochemical staining of the muscle for glycogen revealed a marked depletion in the slow twitch fibres. Only a small glycogen depletion occurred in the fast twitch fibres. This suggests a primary reliance upon slow twitch fibres during prolonged running. The results also point to the limitations of assessing substrate utilization or availability in working fibres from muscle samples with mixed fibre populations.