Department of Movement and Sports Sciences, Ghent University, Ghent, BELGIUM.
Department of Neurological and Movement Sciences, University of Verona, ITALY.
Med Sci Sports Exerc. 2020 May;52(5):1116-1125. doi: 10.1249/MSS.0000000000002236.
Intense exercise evokes a spleen contraction releasing red blood cells into blood circulation. The same mechanism is found after acute apnea, increasing hemoglobin concentration ([Hb]) by 2% to 5%. The aim of this study was twofold: [1] to identify the optimal apnea modalities to acutely increase [Hb] and [2] use these modalities to examine whether prerace apnea can improve a 3-km time trial (TT).
In part 1, 11 male subjects performed 12 different apnea protocols based on three modalities: mode, frequency, and intensity. Venous blood samples for [Hb] were collected before, immediately, and 5 min after each protocol. In part 2, 12 recreationally active subjects performed 3-km cycling TT in three different conditions: apnea, control, and placebo, after a 10-min warm-up. Power output, HR, and oxygen uptake (V˙O2) were continuously measured. Venous [Hb] was sampled at baseline, after warm-up, and before TT. Additionally, these subjects performed constant cycling at Δ25 (25% between gas exchange threshold and V˙O2 max) in two conditions (control and apnea) to determine V˙O2 kinetics.
Although including one single apnea in the warming up evoked a positive change in [Hb] pattern (P = 0.049) and one single apnea seemed to improve V˙O2 kinetics in constant submaximal cycling (τ: P = 0.060, mean response time: P = 0.064), performance during the 3-km TT did not differ between conditions (P = 0.840; apnea, 264.8 ± 14.1 s; control, 263.9 ± 12.9 s, placebo, 264.0 ± 15.8 s). Average normalized power output (P = 0.584) and V˙O2, HR, and lactate did not differ either (P > 0.05).
These results suggest that potential effects of apnea, that is, speeding of V˙O2 kinetics through a transient increase in [Hb], are overruled by a warming-up protocol.
剧烈运动可引起脾脏收缩，将红细胞释放到血液循环中。在急性呼吸暂停后也会发现同样的机制，血红蛋白浓度（[Hb]）增加 2%至 5%。本研究的目的有两个：[1]确定急性增加[Hb]的最佳呼吸暂停方式；[2]使用这些方式来检查赛前呼吸暂停是否可以改善 3 公里计时赛（TT）。
在第 1 部分中，11 名男性受试者根据三种方式进行了 12 种不同的呼吸暂停方案：模式、频率和强度。在每个方案之前、立即和 5 分钟后采集静脉血样以测量[Hb]。在第 2 部分中，12 名休闲活跃的受试者在三种不同条件下进行 3 公里自行车 TT：呼吸暂停、对照和安慰剂，在 10 分钟热身之后。连续测量功率输出、HR 和氧气摄取量（V˙O2）。在基线、热身后和 TT 前采集静脉[Hb]样本。此外，这些受试者在两种条件（对照和呼吸暂停）下进行 25%（呼吸交换阈和 V˙O2max 之间的 25%）恒定循环以确定 V˙O2动力学。
尽管在热身中包含一次单独的呼吸暂停会引起[Hb]模式的积极变化（P = 0.049），并且单次呼吸暂停似乎会改善恒定次最大循环中的 V˙O2 动力学（τ：P = 0.060，平均响应时间：P = 0.064），但在 3 公里 TT 中，条件之间的表现没有差异（P = 0.840；呼吸暂停，264.8 ± 14.1 s；对照，263.9 ± 12.9 s，安慰剂，264.0 ± 15.8 s）。平均归一化功率输出（P = 0.584）和 V˙O2、HR 和乳酸也没有差异（P > 0.05）。
这些结果表明，呼吸暂停的潜在影响，即通过血红蛋白浓度的短暂增加来加速 V˙O2 动力学，被热身方案所取代。
