Failure to repeatedly supercompensate muscle glycogen stores in highly trained men
McInerney, Patrick, Lessard, Sarah J., Burke, Louise M., Coffey, Vernon G., Lo Giudice, Sonia L., Southgate, Robert J., & Hawley, John A. (2005) Failure to repeatedly supercompensate muscle glycogen stores in highly trained men. Medicine and Science in Sports and Exercise, 37(3), pp. 404-411.
Purpose: It is not known whether it is possible to repeatedly supercompensate muscle glycogen stores after exhaustive exercise bouts undertaken within several days.
Methods: We evaluated the effect of repeated exercise-diet manipulation on muscle glycogen and triacylglycerol (IMTG) metabolism and exercise capacity in six well-trained subjects who completed an intermittent, exhaustive cycling protocol (EX) on three occasions separated by 48 h (i.e., days 1, 3, and 5) in a 5-d period. Twenty-four hours before day 1, subjects consumed a moderate (6 g·kg-1)-carbohydrate (CHO) diet, followed by 5 d of a high (12 g·kg-1·d -1)-CHO diet. Muscle biopsies were taken at rest, immediately post-EX on days 1, 3, and 5, and after 3 h of recovery on days 1 and 3.
Results: Compared with day 1, resting muscle [glycogen] was elevated on day 3 but not day 5 (435 ± 57 vs 713 ± 60 vs 409 ± 40 mmol·kg -1, P < 0.001). [IMTG] was reduced by 28% (P < 0.05) after EX on day 1, but post-EX levels on days 3 and 5 were similar to rest. EX was enhanced on days 3 and 5 compared with day 1 (31.9 ± 2.5 and 35.4 ± 3.8 vs 24.1 ± 1.4 kJ·kg-1, P < 0.05). Glycogen synthase activity at rest and immediately post-EX was similar between trials. Additionally, the rates of muscle glycogen accumulation were similar during the 3-h recovery period on days 1 and 3.
Conclusion: We show that well-trained men cannot repeatedly supercompensate muscle [glycogen] after glycogen-depleting exercise and 2 d of a high-CHO diet, suggesting that the mechanisms responsible for glycogen accumulation are attenuated as a consequence of successive days of glycogen-depleting exercise.
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|Item Type:||Journal Article|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > HUMAN MOVEMENT AND SPORTS SCIENCE (110600) > Exercise Physiology (110602)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > NUTRITION AND DIETETICS (111100) > Clinical and Sports Nutrition (111101)
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Current > Schools > School of Exercise & Nutrition Sciences
|Deposited On:||07 Nov 2013 22:35|
|Last Modified:||15 Nov 2013 03:51|
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