Mukai Kazutaka, Ohmura Hajime, Matsui Akira, Aida Hiroko, Takahashi Toshiyuki, Jones James H
Sports Science Division, Equine Research Institute, Japan Racing Association, Utsunomiya, Tochigi, Japan.
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
Physiol Rep. 2020 May;8(10):e14442. doi: 10.14814/phy2.14442.
We examined the effects of high-intensity training in normobaric hypoxia on aerobic capacity and exercise performance in horses and the individual response to normoxic and hypoxic training. Eight untrained horses were studied in a randomized, crossover design after training in hypoxia (HYP; 15.0% inspired O ) or normoxia (NOR; 20.9% inspired O ) 3 days/week for 4 weeks separated by a 4-month washout period. Before and after each training period, incremental treadmill exercise tests were performed in normoxia. Each training session consisted of 1 min cantering at 7 m/s and 2 min galloping at the speed determined to elicit maximal oxygen consumption ( O max) in normoxia. Hypoxia increased significantly more than NOR in run time to exhaustion (HYP, +28.4%; NOR, +10.4%, p = .001), O max (HYP, +12.1%; NOR, +2.6%, p = .042), cardiac output ( ; HYP, +11.3%; NOR, -1.7%, p = .019), and stroke volume (SV) at exhaustion (HYP, +5.4%; NOR, -5.5%, p = .035) after training. No significant correlations were observed between NOR and HYP for individual changes after training in run time (p = .21), O max (p = .99), (p = .19), and SV (p = .46) at exhaustion. Arterial O saturation during exercise in HYP was positively correlated with the changes in run time (r = .85, p = .0073), (r = .72, p = .043) and SV (r = .77, p = .026) of HYP after training, whereas there were no correlations between these parameters in NOR. These results suggest that high-intensity training in normobaric hypoxia improved exercise performance and aerobic capacity of horses to a greater extent than the same training protocol in normoxia, and the severity of hypoxemia during hypoxic exercise might be too stressful for poor responders to hypoxic training.
我们研究了常压低氧环境下高强度训练对马匹有氧能力和运动表现的影响，以及个体对常氧和低氧训练的反应。八匹未经训练的马采用随机交叉设计进行研究，在低氧（HYP；吸入氧含量15.0%）或常氧（NOR；吸入氧含量20.9%）环境下每周训练3天，共4周，中间间隔4个月的洗脱期。在每个训练期前后，在常氧环境下进行递增式跑步机运动测试。每次训练包括以7米/秒的速度慢跑1分钟，以及以在常氧环境下测定的能引发最大耗氧量（VO₂max）的速度疾驰2分钟。训练后，低氧组在力竭跑步时间（HYP，增加28.4%；NOR，增加10.4%，p = 0.001）、VO₂max（HYP，增加12.1%；NOR，增加2.6%，p = 0.042）、心输出量（CO；HYP，增加11.3%；NOR，减少1.7%，p = 0.019）和力竭时的每搏输出量（SV）（HYP，增加5.4%；NOR，减少5.5%，p = 0.035）方面的增加幅度显著高于常氧组。训练后，常氧组和低氧组在力竭跑步时间（p = 0.21）、VO₂max（p = 0.99）、CO（p = 0.19）和SV（p = 0.46）的个体变化之间未观察到显著相关性。低氧组运动期间的动脉血氧饱和度与训练后低氧组的跑步时间变化（r = 0.85，p = 0.0073）、CO（r = 0.72，p = 0.043）和SV（r = 0.77，p = 0.026）呈正相关，而常氧组这些参数之间无相关性。这些结果表明，常压低氧环境下的高强度训练比常氧环境下相同训练方案能更大程度地提高马匹的运动表现和有氧能力，并且低氧运动期间的低氧血症严重程度对低氧训练反应不佳的马匹可能压力过大。
