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Impact of carbohydrate supplementation during endurance training on glycogen storage and performance

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Abstract Aim: Glucose ingestion may improve exercise endurance, but it apparently also influences the transcription rate of several metabolic genes and it alters muscle metabolism during an acute exercise bout. Therefore, we investigated how chronic training responses are affected by glucose ingestion. Methods: In previously untrained males performance and various muscular adaptations were evaluated before and after 8 weeks of supervised endurance training conducted either with (n = 8; CHO group) or without (n = 7; placebo) glucose supplementation. Results: The two groups achieved similar improvements in maximal oxygen uptake and peak power output during incremental cycling (both parameters elevated by 17% on average) and both groups lost approximately 3 kg of fat mass during the 8 weeks of training. An equal reduction in respiratory exchange ratio (0.02 units) during submaximal exercise was observed in both groups. Beta-hydroxyacyl-CoA-dehydrogenase activity was increased in both groups, however, to a larger extent in the placebo group (45 +/- 11%) than CHO (23 +/- 9%, P < 0.05). GLUT-4 protein expression increased by 74 +/- 14% in the placebo group and 45 +/- 14% in CHO (both P < 0.05), while resting muscle glycogen increased (P < 0.05) to a larger extent in the placebo group (96 +/- 4%) than CHO (33 +/- 2%). Conclusion: These results show that carbohydrate supplementation consumed during exercise training influences various muscular training adaptations, but improvements in cardiorespiratory fitness and reductions in fat mass are not affected.
OriginalsprogEngelsk
TidsskriftActa Physiologica (Print Edition)
Vol/bind197
Udgave nummer2
Sider (fra-til)117-127
Antal sider11
ISSN1748-1708
DOI
StatusUdgivet - 2009

Bibliografisk note

CURIS 2009 5200 102

ID: 14022835