Foskett Andrew, Williams Clyde, Boobis Leslie, Tsintzas Kostas
Institute of Food, Nutrition and Human Health, Massey University, Auckland, New Zealand.
Med Sci Sports Exerc. 2008 Jan;40(1):96-103. doi: 10.1249/mss.0b013e3181586b2c.
To examine the influence of ingesting a carbohydrate-electrolyte (CHO-E) solution on muscle glycogen use and intermittent running capacity after consumption of a carbohydrate (CHO)-rich diet.
Six male volunteers (mean +/- SD: age 22.7 +/- 3.4 yr; body mass (BM) 75.0 +/- 4.3 kg; V O2 max 60.2 +/- 1.6 mL x kg(-1) x min(-1)) performed two trials separated by 14 d in a randomized, crossover design. Subjects consumed either a 6.4% CHO-E solution or a placebo (PLA) in a double-blind fashion immediately before each trial (8 mL x kg(-1) BM) and at 15-min intervals (3 mL x kg(-1) BM) during intermittent high-intensity running to fatigue performed after CHO loading for 2 d. Muscle biopsy samples were obtained before exercise, after 90 min of exercise, and at fatigue.
Subjects ran longer in the CHO-E trial (158.0 +/- 28.4 min) compared with the PLA trial (131.0 +/- 19.7 min; P < 0.05). There were no differences in muscle glycogen use for the first 90 min of exercise (approximately 2 mmol of glucosyl units per kilogram of dry matter (DM) per minute). However, there was a trend for a greater use in the PLA trial after 90 min (4.2 +/- 2.8 mmol x kg(-1) DM x min(-1)) compared with the CHO-E trial (2.5 +/- 0.7 mmol x kg(-1) DM x min(-1); P = 0.10). Plasma glucose concentrations were higher at fatigue in the CHO-E than in the PLA trial (P < 0.001).
These results suggest that CHO-E ingestion improves endurance capacity during intermittent high-intensity running in subjects with high preexercise muscle glycogen concentrations. The greater endurance capacity cannot be explained solely by differences in muscle glycogen, and it may actually be a consequence of the higher plasma glucose concentration towards the end of exercise that provided a sustained source of CHO for muscle metabolism and for the central nervous system.
研究摄入碳水化合物 - 电解质（CHO - E）溶液对食用富含碳水化合物（CHO）饮食后肌肉糖原利用和间歇性跑步能力的影响。
六名男性志愿者（平均±标准差：年龄22.7±3.4岁；体重（BM）75.0±4.3千克；最大摄氧量60.2±1.6毫升·千克⁻¹·分钟⁻¹）采用随机交叉设计，进行了两项间隔14天的试验。在每次试验前（8毫升·千克⁻¹体重）以及在CHO负荷2天后进行的间歇性高强度跑步至疲劳期间，每隔15分钟（3毫升·千克⁻¹体重），受试者以双盲方式分别饮用6.4%的CHO - E溶液或安慰剂（PLA）。在运动前、运动90分钟后和疲劳时采集肌肉活检样本。
与PLA试验（131.0±19.7分钟）相比，受试者在CHO - E试验中跑步时间更长（158.0±28.4分钟；P<0.05）。运动前90分钟肌肉糖原的利用情况无差异（约每分钟每千克干物质（DM）2毫摩尔葡萄糖单位）。然而，90分钟后，PLA试验中的糖原利用趋势高于CHO - E试验（4.2±2.8毫摩尔·千克⁻¹ DM·分钟⁻¹）（2.5±0.7毫摩尔·千克⁻¹ DM·分钟⁻¹；P = 0.10）。CHO - E试验中疲劳时的血浆葡萄糖浓度高于PLA试验（P<0.001）。
这些结果表明，对于运动前肌肉糖原浓度较高的受试者，摄入CHO - E可提高间歇性高强度跑步期间的耐力。更大的耐力不能仅由肌肉糖原的差异来解释，实际上可能是运动末期较高的血浆葡萄糖浓度所致，它为肌肉代谢和中枢神经系统提供了持续的CHO来源。
