Rowlands David S, Hopkins Will G
Department of Exercise Science in the Institute of Food, Nutrition, and Human Health and Massey University, Private Bag 756, Wellington, New Zealand.
Int J Sport Nutr Exerc Metab. 2002 Sep;12(3):318-35. doi: 10.1123/ijsnem.12.3.318.
The effect of pre-exercise meal composition on metabolism and performance in cycling were investigated in a crossover study. Twelve competitive cyclists ingested high-fat, high-carbohydrate, or high-protein meals 90 min before a weekly exercise test. The test consisted of a 1-hour pre-load at 55% peak power, five 10-min incremental loads from 55 to 82% peak power (to measure the peak fat-oxidation rate), and a 50-km time trial that included three 1-km and 4-km sprints. A carbohydrate supplement was ingested throughout the exercise. Relative to the high-protein and high-fat meals, the high-carbohydrate meal halved the peak fat-oxidation rate and reduced the fat oxidation across all workloads by a factor of 0.20 to 0.58 (p =.002-.0001). Reduced fat availability may have accounted for this reduction, as indicated by lower plasma fatty acid, lower glycerol, and higher pre-exercise insulin concentrations relative to the other meals (p =.04-.0001). In contrast, fat oxidation following the high-protein meal was similar to that following the high-fat meal. This similarity was linked to evidence suggesting greater lipolysis and plasma fat availability following high-protein relative to high-carbohydrate meals. Despite these substantial effects on metabolism, meal composition had no clear effect on sprint or 50-km performance.
在一项交叉研究中，研究了运动前膳食组成对自行车运动中新陈代谢和运动表现的影响。12名竞技自行车运动员在每周一次的运动测试前90分钟摄入高脂肪、高碳水化合物或高蛋白膳食。测试包括在55%峰值功率下进行1小时的预负荷，从55%到82%峰值功率进行五次10分钟的递增负荷（以测量峰值脂肪氧化率），以及一次50公里的计时赛，其中包括三次1公里和4公里的冲刺。在整个运动过程中摄入碳水化合物补充剂。相对于高蛋白和高脂肪膳食，高碳水化合物膳食使峰值脂肪氧化率减半，并使所有工作负荷下的脂肪氧化减少0.20至0.58倍（p = 0.002 - 0.0001）。相对于其他膳食，血浆脂肪酸降低、甘油降低以及运动前胰岛素浓度升高表明，脂肪可用性降低可能是导致这种减少的原因（p = 0.04 - 0.0001）。相比之下，高蛋白膳食后的脂肪氧化与高脂肪膳食后的相似。这种相似性与以下证据有关，即相对于高碳水化合物膳食，高蛋白膳食后脂肪分解和血浆脂肪可用性更高。尽管对新陈代谢有这些显著影响，但膳食组成对冲刺或50公里的运动表现没有明显影响。
