Al Haddad Hani, Mendez-Villanueva Alberto, Bourdon Pitre C, Buchheit Martin
Physiology Unit, Sport Science Department, Aspire Academy for Sports Excellence Doha, Qatar.
Front Physiol. 2012 Jul 25;3:289. doi: 10.3389/fphys.2012.00289. eCollection 2012.
In this study we assessed the effect of acute hypoxia on post-exercise parasympathetic reactivation inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Ten healthy males participated in this study. Following 10 min of seated rest, participants performed 5 min of submaximal running at the speed associated with the first ventilatory threshold (Sub) followed by a 20-s all-out supramaximal sprint (Supra). Both Sub and Supra runs were immediately followed by 15 min of seated passive recovery. The resting and exercise sequence were performed in both normoxia (N) and normobaric hypoxia (H; FiO(2) = 15.4%). HRR indices (e.g., heart beats recovered in the first minute after exercise cessation, HRR(60s)) and vagal-related HRV indices [i.e., natural logarithm of the square root of the mean of the sum of the squared differences between adjacent normal R-R intervals (Ln rMSSD)] were calculated for both conditions. Difference in the changes between N and H for all HR-derived indices were also calculated for both Sub and Supra. HRR(60s) was greater in N compared with H following Sub only (60 ± 14 vs. 52 ± 19 beats min(-1), P = 0.016). Ln rMSSD was greater in N compared with H (post Sub: 3.60 ± 0.45 vs. 3.28 ± 0.44 ms in N and H, respectively, and post Supra: 2.66 ± 0.54 vs. 2.65 ± 0.63 ms, main condition effect P = 0.02). When comparing the difference in the changes, hypoxia decreased HRR(60s) (-14.3% ± 17.2 vs. 5.2% ± 19.3; following Sub and Supra, respectively; P = 0.03) and Ln rMSSD (-8.6% ± 7.0 vs. 2.0% ± 13.3, following Sub and Supra, respectively; P = 0.08, Cohen's effect size = 0.62) more following Sub than Supra. While hypoxia may delay parasympathetic reactivation following submaximal exercise, its effect is not apparent following supramaximal exercise. This may suggest that the effect of blood O(2) partial pressure on parasympathetic reactivation is limited under heightened sympathetic activation.
在本研究中，我们评估了急性低氧对运动后副交感神经再激活的影响，该影响通过心率（HR）恢复（HRR）和HR变异性（HRV）指标推断得出。十名健康男性参与了本研究。在静坐休息10分钟后，参与者以与第一通气阈值相关的速度进行5分钟次最大强度跑步（次最大强度运动，Sub），随后进行20秒全力超最大强度冲刺（超最大强度运动，Supra）。Sub和Supra运动后均紧接着进行15分钟的静坐被动恢复。静息和运动序列在常氧（N）和常压低氧（H；吸入氧分数FiO₂ = 15.4%）条件下均进行。计算了两种条件下的HRR指标（例如，运动停止后第一分钟内恢复的心跳数，HRR(60s)）和与迷走神经相关的HRV指标[即相邻正常R-R间期平方差总和的平均值的平方根的自然对数（Ln rMSSD）]。还计算了Sub和Supra运动后N和H之间所有HR衍生指标变化的差异。仅在Sub运动后，N组的HRR(60s)高于H组（分别为60 ± 14次/分钟和52 ± 19次/分钟，P = 0.016）。N组的Ln rMSSD高于H组（Sub运动后：N组和H组分别为3.60 ± 0.45毫秒和3.28 ± 0.44毫秒，Supra运动后：分别为2.66 ± 0.54毫秒和2.65 ± 0.63毫秒，主要条件效应P = 0.02）。在比较变化差异时，低氧使HRR(60s)降低的幅度更大（分别在Sub和Supra运动后为-14.3% ± 17.2和5.2% ± 19.3；P = 0.03），使Ln rMSSD降低的幅度更大（分别在Sub和Supra运动后为-8.6% ± 7.0和2.0% ± 13.3；P = 0.08，科恩效应量 = 0.62），Sub运动后的降低幅度大于Supra运动后。虽然低氧可能会延迟次最大强度运动后副交感神经的再激活，但在超最大强度运动后其影响并不明显。这可能表明在交感神经激活增强的情况下，血液氧分压对副交感神经再激活的影响是有限的。
