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Metabolic demands and replenishment of muscle glycogen after a rugby league match simulation protocol.
Bradley, Warren J. Hannon, Marcus P. Benford, Victoria Morehen, James C. Twist, Craig Shepherd, Sam Cocks, Matthew Impey, Samuel G. Cooper, Robert G. Morton, James P.
Bradley, Warren J.
Hannon, Marcus P.
Benford, Victoria
Morehen, James C.
Twist, Craig
Shepherd, Sam
Cocks, Matthew
Impey, Samuel G.
Cooper, Robert G.
Morton, James P.
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2017-02-22
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Abstract
Objectives: The metabolic requirements of a rugby league match simulation protocol and the timing of carbohydrate provision on glycogen re-synthesis in damaged muscle were examined. Design: Fifteen (mean ± SD: age 20.9 ± 2.9 y, body-mass 87.3 ± 14.1 kg, height 177.4 ± 6.0 cm) rugby league (RL) players consumed a 6 g•kg•day-1 CHO diet for 7-days, completed a time to exhaustion test (TTE) and a glycogen depletion protocol on day-3, a RL simulated-match protocol (RLMSP) on day-5 and a TTE on day-7. Players were prescribed an immediate or delayed (2-h-post) re-feed post-simulation. Methods: Muscle biopsies and blood samples were obtained post-depletion, before and after simulated match-play, and 48-h after match-play with PlayerLoad and heart-rate collected throughout the simulation. Data were analysed using effects sizes ± 90% CI and magnitude-based inferences. Results: PlayerLoad (8.0 ± 0.7 AU•min-1) and %HRpeak (83 ± 4.9%) during the simulation were similar to values reported for RL match-play. Muscle glycogen very likely increased from immediately after to 48-h post-simulation (272 ± 97 cf. 416 ± 162 mmol•kg-1d.w.; ES ± 90%CI) after immediate re-feed, but changes were unclear (283 ± 68 cf. 361 ± 144 mmol•kg-1d.w.; ES ± 90%CI) after delayed re-feed. CK almost certainly increased by 77.9 ± 25.4% (0.75 ± 0.19) post-simulation for all players. Conclusions: The RLMSP presents a replication of the internal loads associated with professional RL match-play, although difficulties in replicating the collision reduced the metabolic demands and glycogen utilisation. Further, it is possible to replete muscle glycogen in damaged muscle employing an immediate re-feed strategy.
Citation
Bradley, W. J., Hannon, M. P., Benford, V., Morehen, J. C., Twist, C., Shepherd, S., Cocks, M., Impey, S. G., Cooper, R. G., Morton, J. P. & Close, G. L. (2017). Metabolic demands and replenishment of muscle glycogen after simulated rugby match play. Journal of Science and Medicine in Sport, 20(9), 878-883.
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en
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1440-2440
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1878-1861