Carbohydrate loading failed to improve 100-km cycling performance in a placebo-controlled trial

被引:44
作者
Burke, LM
Hawley, JA
Schabort, EJ
Gibson, ASC
Mujika, I
Noakes, TD
机构
[1] Univ Cape Town, Sch Med, MRC,Dept Physiol, Univ Cape Town Bioenerget Exercise Res Unit, ZA-7701 Cape Town, South Africa
[2] Australian Inst Sport, Dept Sports Nutr, Canberra, ACT 2616, Australia
[3] RMIT Univ, Dept Human Biol & Movement Sci, Exercise Metab Grp, Bundoora, Vic 3083, Australia
[4] Athlet Club Bilbao, Dept Invest, Bilbao, Bacque Country, Spain
[5] Athlet Club Bilbao, Desarollo Serv Med, Bilbao, Bacque Country, Spain
关键词
glycogen loading; road cycling; blood glucose;
D O I
10.1152/jappl.2000.88.4.1284
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
We evaluated the effect of carbohydrate (CHO) loading on cycling performance that was designed to be similar to the demands of competitive road racing. Seven well-trained cyclists performed two 100-km time trials (TTs) on separate occasions, 3 days after either a CHO-loading (9 g CHO kg body mass-l day-l) or placebo-controlled moderate-CHO diet (6 g CHO kg body mass-l day(-1)). A CHO breakfast (2 g CHO/kg body mass) was consumed 2 h before each TT, and a CHO drink (1 g CHO kg.body mass-l-h-l) was consumed during the TTs to optimize CHO availability. The 100-km TT was interspersed with four 4-km and five l-km sprints. CHO loading significantly increased muscle glycogen concentrations (572 +/- 107 vs. 485 +/- 128 mmol/kg dry mt for CRO loading and placebo, respectively; P < 0.05). Total muscle glycogen utilization did not differ between trials, nor did time to complete the TIS (147.5 +/- 10.0 and 149.1 +/- 11.0 min; P = 0.4) or the mean power output during the TTs (259 +/- 40 and 253 +/-: 40 W; P = 0.4). This placebo-controlled study shows that CHO loading did not improve performance of a 100-km cycling IT during which CHO was consumed. By preventing any fall in blood glucose concentration, CHO ingestion during exercise may offset any detrimental effects on performance of lower preexercise muscle and liver glycogen concentrations. Alternatively, part of the reported benefit of CHO loading on subsequent athletic performance could have resulted from a placebo effect.
引用
收藏
页码:1284 / 1290
页数:7
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