Muscle glycogen utilisation during Rugby match play: Effects of pre-game carbohydrate. Issue 12 (December 2016)

• Record Type: Journal Article
• Authors: Bradley, Warren J.; Morehen, James C.; Haigh, Julian; Clarke, Jon; Donovan, Timothy F.; Twist, Craig; Cotton, Caroline; Shepherd, Sam; Cocks, Matthew; Sharma, Asheesh; Impey, Samuel G.; Cooper, Robert G.; Maclaren, Don P.M.; Morton, James P.; Close, Graeme L.
• Is Part Of: Journal of science and medicine in sport. Volume 19:Issue 12(2016)
• Page Start: 1033
• Page End: 1038
• Publication Date: 2016-12
• Subjects: Competition -- GPS -- Physiology -- Nutrition -- Team-sport -- Metabolism; Sports sciences -- Periodicals; Sports medicine -- Periodicals; Exercise -- Physiological aspects -- Periodicals; Sports -- physiology -- Periodicals; Sports Medicine -- Periodicals; Sportgeneeskunde; 617.102705
• DOI: 10.1016/j.jsams.2016.03.008
• Languages: English
• ISSNs: 1440-2440

Abstract

Abstract: Objectives: Although the physical demands of Rugby League (RL) match-play are well-known, the fuel sources supporting energy-production are poorly understood. We therefore assessed muscle glycogen utilisation and plasma metabolite responses to RL match-play after a relatively high (HCHO) or relatively low CHO (LCHO) diet. Design: Sixteen (mean ± SD age; 18 ± 1 years, body-mass; 88 ± 12 kg, height 180 ± 8 cm) professional players completed a RL match after 36-h consuming a non-isocaloric high carbohydrate ( n = 8; 6 g kg day −1 ) or low carbohydrate ( n = 8; 3 g kg day −1 ) diet. Methods: Muscle biopsies and blood samples were obtained pre- and post-match, alongside external and internal loads quantified using Global Positioning System technology and heart rate, respectively. Data were analysed using effects sizes ±90% CI and magnitude-based inferences. Results: Differences in pre-match muscle glycogen between high and low carbohydrate conditions (449 ± 51 and 444 ± 81 mmol kg −1 d.w.) were unclear . High (243 ± 43 mmol kg −1 d.w.) and low carbohydrate groups (298 ± 130 mmol kg −1 d.w.) were most and very likely reduced post-match, respectively. For both groups, differences in pre-match NEFA and glycerol were unclear, with a most likely increase in NEFA and glycerol post-match. NEFA was likely lower in the high compared with low carbohydrate group post-match (0.95 ± 0.39 mmol l −1 and 1.45 ± 0.51 mmol l −1, respectively), whereas differences between the 2 groups for glycerol were unclear (98.1 ± 33.6 mmol l −1 and 123.1 ± 39.6 mmol l −1 ) in the high and low carbohydrate groups, respectively. Conclusions: Professional RL players can utilise ∼40% of their muscle glycogen during a competitive match regardless of their carbohydrate consumption in the preceding 36-h.