O'Hara John P, Woods David R, Mellor Adrian, Boos Christopher, Gallagher Liam, Tsakirides Costas, Arjomandkhah Nicola C, Holdsworth David A, Cooke Carlton B, Morrison Douglas J, Preston Thomas, King Roderick Fgj
Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, United Kingdom
Research Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Leeds, United Kingdom.
Physiol Rep. 2017 Jan;5(1). doi: 10.14814/phy2.13101.
This study compared the effects of coingesting glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at altitude and sea level, in men. Seven male British military personnel completed two bouts of cycling at the same relative workload (55% W) for 120 min on acute exposure to altitude (3375 m) and at sea level (~113 m). In each trial, participants ingested 1.2 g·min of glucose (enriched with C glucose) and 0.6 g·min of fructose (enriched with C fructose) directly before and every 15 min during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation, and endogenous glucose oxidation derived from liver and muscle glycogen. Total carbohydrate oxidation during the exercise period was lower at altitude (157.7 ± 56.3 g) than sea level (286.5 ± 56.2 g, P = 0.006, ES = 2.28), whereas fat oxidation was higher at altitude (75.5 ± 26.8 g) than sea level (42.5 ± 21.3 g, P = 0.024, ES = 1.23). Peak exogenous carbohydrate oxidation was lower at altitude (1.13 ± 0.2 g·min) than sea level (1.42 ± 0.16 g·min, P = 0.034, ES = 1.33). There were no differences in rates, or absolute and relative contributions of plasma or liver glucose oxidation between conditions during the second hour of exercise. However, absolute and relative contributions of muscle glycogen during the second hour were lower at altitude (29.3 ± 28.9 g, 16.6 ± 15.2%) than sea level (78.7 ± 5.2 g (P = 0.008, ES = 1.71), 37.7 ± 13.0% (P = 0.016, ES = 1.45). Acute exposure to altitude reduces the reliance on muscle glycogen and increases fat oxidation during prolonged cycling in men compared with sea level.
本研究比较了男性在高原和海平面进行长时间运动时同时摄入葡萄糖和果糖对外源性和内源性底物氧化的影响。七名英国男性军事人员在急性暴露于高原（3375米）和海平面（约113米）时，以相同的相对工作量（55%W）完成了两轮120分钟的骑行。在每次试验中，参与者在运动前直接摄入1.2克·分钟的葡萄糖（富含碳葡萄糖）和0.6克·分钟的果糖（富含碳果糖），并在运动期间每15分钟摄入一次。使用间接量热法和同位素比率质谱法计算脂肪氧化、总碳水化合物和外源性碳水化合物氧化、血浆葡萄糖氧化以及源自肝脏和肌肉糖原的内源性葡萄糖氧化。运动期间的总碳水化合物氧化在高原（157.7±56.3克）低于海平面（286.5±56.2克，P=0.006，效应量=2.28），而脂肪氧化在高原（75.5±26.8克）高于海平面（42.5±21.3克，P=0.024，效应量=1.23）。高原的外源性碳水化合物氧化峰值（1.13±0.2克·分钟）低于海平面（1.42±0.16克·分钟，P=0.034，效应量=1.33）。在运动的第二个小时内，不同条件下血浆或肝脏葡萄糖氧化的速率、绝对和相对贡献没有差异。然而，在第二个小时内，高原肌肉糖原的绝对和相对贡献（29.3±28.9克，16.6±15.2%）低于海平面（78.7±5.2克（P=0.008，效应量=1.71），37.7±13.0%（P=0.016，效应量=1.45）。与海平面相比，急性暴露于高原会降低男性在长时间骑行过程中对肌肉糖原的依赖并增加脂肪氧化。
