Bosch A N, Weltan S M, Dennis S C, Noakes T D
The MRC/UCT Bioenergetics of Exercise Research Unit, Department of Physiology, Sports Science Institute of South Africa, University of Cape Town, Boundary Road, Newlands 7925, South Africa.
Pflugers Arch. 1996 Oct;432(6):1003-10. doi: 10.1007/s004240050228.
This study examined the effects of ingesting 500 ml/h of either a 10% carbohydrate (CHO) drink (CI) or placebo (PI) on splanchnic glucose appearance rate (endogenous + exogenous) (Ra), plasma glucose oxidation and muscle glycogen utilisation in 17, non-carbohydrate-loaded, male, endurance-trained cyclists who rode for 180 min at 70% of maximum oxygen uptake. Mean muscle glycogen content at the start of exercise was 130 +/- 6 mmol/kg ww; (mean +/- SEM). Total CHO oxidation was similar in CI and PI subjects and declined during the trial. Ra increased significantly during the trial (P < 0.05) in both groups. Plasma glucose oxidation also increased significantly during the trial, reaching a plateau in the PI subjects, but was significantly (P < 0.05) higher in CI than PI subjects at the end of exercise [(98 +/- 14 vs. 72 +/- 10 micromol/min/kg fat-free mass) (FFM) (1.34 +/- 0.19 vs. 0.93 +/- 0. 13 g/min)]. However, mean endogenous Ra was significantly (P < 0.05) lower in the CI than PI subjects throughout exercise (35 +/- 7 vs. 54 +/- 6 micromol/min/kg FFM), as was the oxidation of endogenous plasma glucose, which remained almost constant in CI subjects, and reached values at the end of exercise of 42 +/- 13 and 72 +/- 10 micromol/min/kg FFM in the CI and PI groups respectively. Of the 150 g CHO ingested during the trial, 50% was oxidised. Muscle glycogen disappearance was identical during the first 2 h of exercise in both groups and continued at the same rate in PI subjects, however no net muscle glycogen disappearance occurred during the final hour in CI subjects. We conclude that ingestion of 500 ml/h of a 10% CHO solution during prolonged exercise in non carbohydrate loaded subjects has a marked liver glycogen-sparing effect or causes a reduction in gluconeogenesis, or both, maintains plasma glucose concentration and has a muscle glycogen-sparing effect.
本研究检测了17名未摄入碳水化合物、进行耐力训练的男性自行车运动员，以70%最大摄氧量骑行180分钟期间，每小时摄入500毫升10%碳水化合物（CHO）饮料（CI）或安慰剂（PI）对内脏葡萄糖出现率（内源性+外源性）（Ra）、血浆葡萄糖氧化及肌肉糖原利用的影响。运动开始时肌肉糖原平均含量为130±6毫摩尔/千克湿重；（平均值±标准误）。CI组和PI组受试者的总CHO氧化相似，且在试验期间下降。两组的Ra在试验期间均显著增加（P<0.05）。试验期间血浆葡萄糖氧化也显著增加，PI组受试者达到平台期，但运动结束时CI组显著高于PI组（P<0.05）[（98±14对72±10微摩尔/分钟/千克去脂体重）（FFM）（1.34±0.19对0.93±0.13克/分钟）]。然而，整个运动过程中CI组的平均内源性Ra显著低于PI组（P<0.05）（35±7对54±6微摩尔/分钟/千克FFM），内源性血浆葡萄糖的氧化也是如此，CI组受试者几乎保持恒定，运动结束时CI组和PI组的值分别为42±13和72±10微摩尔/分钟/千克FFM。试验期间摄入的150克CHO中有50%被氧化。两组在运动的前2小时肌肉糖原消失情况相同，PI组受试者以相同速率继续，但CI组受试者在最后1小时没有净肌肉糖原消失。我们得出结论，在未摄入碳水化合物的受试者进行长时间运动期间，每小时摄入500毫升10%的CHO溶液具有显著的肝脏糖原节省效应或导致糖异生减少，或两者兼有，维持血浆葡萄糖浓度并具有肌肉糖原节省效应。
