Katayama K, Sato K, Hotta N, Ishida K, Iwasaki K, Miyamura M
Research Center of Health, Physical Fitness and Sports, Nagoya University, Furocho, Chikusaku, Nagoya 464-8601, Japan.
Int J Sports Med. 2007 Jun;28(6):480-7. doi: 10.1055/s-2006-955895. Epub 2007 Mar 15.
Recent human studies have shown that resting hypoxic ventilatory response (HVR), which is an index of ventilatory chemosensitivity to hypoxia, increased after short-term intermittent hypoxia at rest. In addition, intermittent hypoxia leads to increases in ventilation and arterial oxygen saturation (SaO (2)) during exercise at simulated high altitude, with the increase in ventilation correlated to the change in HVR. However, no study has been made to clarify the relationship between ventilatory chemosensitivity and the exercise ventilation at moderate altitude following intermittent hypoxia during a resting state. The purpose of the present study, therefore, was to elucidate whether intermittent hypoxia at rest induces the increase in ventilation during exercise at moderate altitude that is accompanied by an increase in hypoxic chemosensitivity. Eighteen trained male runners were assigned to three groups, i.e., the first hypoxic group (H-1 group, n = 6), the second hypoxic group (H-2 group, n = 6), and a control group (C group, n = 6). The hypoxic tent system was utilized for intermittent hypoxia, and the oxygen levels in the tent were maintained at 15.5 +/- 0.1 % (simulated 2500 m altitude) for the H-1 group and 12.3 +/- 0.2 % (simulated 4300 m altitude) for the H-2 group. The H-1 and H-2 groups spent 1 hour per day in the hypoxic tent for 1 week. Maximal and submaximal exercise tests while breathing 15.5 +/- 0.01 % O (2) (simulated altitude of 2500 m) were performed before and after intermittent hypoxia. Resting HVR was also determined in each subject using a progressive isocapnic hypoxic method. In the H-2 group, HVR increased significantly (p < 0.05) following intermittent hypoxia, while no change in HVR was found in the H-1 or C group. Neither ventilation nor SaO (2) during maximal and submaximal exercise at a simulated altitude of 2500 m were changed in either group after 1 hour per day for 1 week of intermittent hypoxia. These results suggest that the change in resting hypoxic chemosensitivity after short-term intermittent hypoxia does not affect ventilation during exercise at moderate altitude.
近期人体研究表明，静息低氧通气反应（HVR）作为对低氧通气化学敏感性的一项指标，在静息状态下短期间歇性低氧后有所增加。此外，间歇性低氧会导致在模拟高海拔运动期间通气量和动脉血氧饱和度（SaO₂）增加，且通气量的增加与HVR的变化相关。然而，尚无研究阐明静息状态下间歇性低氧后，在中等海拔运动时通气化学敏感性与运动通气之间的关系。因此，本研究的目的是阐明静息状态下的间歇性低氧是否会导致中等海拔运动期间通气量增加，并伴有低氧化学敏感性增加。18名受过训练的男性跑步者被分为三组，即第一低氧组（H-1组，n = 6）、第二低氧组（H-2组，n = 6）和对照组（C组，n = 6）。使用低氧帐篷系统进行间歇性低氧，H-1组帐篷内的氧含量维持在15.5±0.1%（模拟海拔2500米），H-2组维持在12.3±0.2%（模拟海拔4300米）。H-1组和H-2组每天在低氧帐篷内待1小时，持续1周。在间歇性低氧前后，进行了在呼吸15.5±0.01% O₂（模拟海拔2500米）时的最大和次最大运动测试。还使用渐进等碳酸低氧法测定了每个受试者的静息HVR。在H-2组中，间歇性低氧后HVR显著增加（p < 0.05），而H-1组或C组中未发现HVR有变化。在每天1小时、持续1周的间歇性低氧后，两组在模拟海拔2500米进行最大和次最大运动时的通气量和SaO₂均未改变。这些结果表明，短期间歇性低氧后静息低氧化学敏感性的变化不会影响中等海拔运动期间的通气量。
