Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan.
Metabolism. 2010 Jul;59(7):959-66. doi: 10.1016/j.metabol.2009.10.017. Epub 2009 Dec 29.
Recent studies have shown that exercise training at moderate altitude or in moderate hypoxia improved glycemic parameters. From these data, it has been supposed that endurance exercise in moderate hypoxia affects substrate utilization and that exposure to moderate hypoxia in combination with exercise may be utilized as part of metabolic or diabetes prevention program. However, the influence of exercise at moderate hypoxia on circulating metabolites and hormones in terms of substrate utilization is unclear. The purpose of this study was to elucidate the influence of exercise in moderate hypoxia on substrate utilization. We determined cardiorespiratory, metabolic, and hormonal parameters during exercise and postexercise recovery at a simulated moderate altitude of 2000 m, and then we compared these variables with values obtained at sea level. Seven men participated in this study; subjects reported to the laboratory on 4 occasions. Two maximal exercise tests were performed to estimate peak oxygen uptake at the simulated 2000-m altitude and sea level on different days. Afterward, submaximal exercise tests were carried out at a simulated altitude of 2000 m or sea level, separated by 1 week. Subjects performed submaximal exercise at the same relative exercise intensity (50% peak oxygen uptake) at a simulated altitude of 2000 m and at sea level for 30 minutes. The tests were performed in random order, and subjects were blinded to the respective altitudes. Venous blood samples and expired gases were obtained before, during exercise (15 and 30 minutes), and during postexercise recovery periods (15, 30, 45, and 60 minutes). The respiratory exchange ratio during exercise and recovery at moderate altitude was greater than at sea level. The epinephrine and norepinephrine concentrations during exercise and recovery were higher (P < .05) at moderate altitude than at sea level. Free fatty acids and glycerol concentrations during recovery were lower (P < .05) at moderate altitude than at sea level. These results suggest that carbohydrate utilization is increased during exercise and postexercise recovery period in moderate hypoxia as compared with normoxia. It is also suggested that moderate hypoxia influences the changes in circulating metabolites and hormones in terms of substrate metabolism during exercise and the recovery.
最近的研究表明，在中等海拔或中度低氧环境下进行运动训练可以改善血糖参数。根据这些数据，人们推测，在中度低氧环境下进行耐力运动可以影响底物的利用，并且在中度低氧环境下暴露并结合运动可能被用作代谢或糖尿病预防计划的一部分。然而，中等低氧运动对循环代谢物和激素在底物利用方面的影响尚不清楚。本研究的目的是阐明中等低氧运动对底物利用的影响。我们在模拟海拔 2000 米的环境下进行运动和运动后恢复期间测定心肺功能、代谢和激素参数，然后将这些变量与海平面的测量值进行比较。7 名男性参与了这项研究；受试者在 4 天内报告至实验室。在不同的日子里，进行了两次最大运动测试，以估计在模拟 2000 米海拔和海平面的峰值摄氧量。之后，在模拟海拔 2000 米或海平面进行了亚最大运动测试，间隔 1 周。受试者在模拟海拔 2000 米和海平面下以相同的相对运动强度（50%的峰值摄氧量）进行 30 分钟的亚最大运动。测试以随机顺序进行，受试者对各自的海拔均不知情。在运动前、运动期间（15 分钟和 30 分钟）和运动后恢复期间（15 分钟、30 分钟、45 分钟和 60 分钟）采集静脉血样和呼出气体。运动和恢复期间的呼吸交换率在中等海拔时大于海平面。运动和恢复期间，肾上腺素和去甲肾上腺素的浓度（P <.05）在中等海拔时高于海平面。恢复期间，游离脂肪酸和甘油的浓度（P <.05）在中等海拔时低于海平面。这些结果表明，与常氧相比，在中等低氧环境下运动和运动后恢复期间碳水化合物的利用率增加。此外，还表明中度低氧会影响运动和恢复期间循环代谢物和激素在底物代谢方面的变化。
