Centre for Sport Research, Deakin University, Geelong, Victoria, AUSTRALIA.
Institute for Physical Activity and Nutrition, Deakin University, Geelong, Victoria, AUSTRALIA.
Med Sci Sports Exerc. 2022 Sep 1;54(9):1506-1514. doi: 10.1249/MSS.0000000000002930. Epub 2022 Apr 8.
Heart rate variability (HRV) has shown sensitivity to the acute stressors experienced by defense personnel. This study examines the suitability of overnight HRV as a repeated measure of allostatic load in defense personnel.
Daily measures of sleep, cognitive load, and perceived exertion were reported for the 12-wk duration of basic military training (BMT) in 48 recruits. Physical activity, subjective well-being, and HRV were measured weekly. The natural log of the root mean square of successive differences of interbeat intervals (Ln RMSSD) and the Ln RMSSD to interbeat interval ratio (Ln RMSSD:RRi ratio) during predicted slow wave sleep were used for HRV. Physical performance was assessed via the 20-m shuttle run and maximal push-up test in weeks 2 and 8 of BMT with predicted V̇O 2 peak values calculated.
Predicted V̇O 2 peak increased from 42.6 ± 4.5 to 48.0 ± 2.7 mL·kg -1 ·min -1 ( P < 0.001). Ln RMSSD was elevated in weeks 7 and 10, and the Ln RMSSD:RRi ratio was elevated in week 10 above all other weeks ( P < 0.05). An increase in perceived exertion ( F = 9.10, P = 0.003) and subjective fatigue ( F = 6.97, P = 0.009), as well as a reduction in V̇O 2 peak ( F = 7.95, P = 0.009), individually predicted an increase in Ln RMSSD. The best predictive model of Ln RMSSD included perceived exertion ( F = 8.16, P = 0.005), subjective fatigue ( F = 8.49, P = 0.004), the number of awakenings during sleep ( F = 7.79, P = 0.006), and the change in V̇O 2 peak ( F = 19.110, P < 0.001).
HRV was predicted by subjective recruit responses to BMT workloads rather than objective measures of physical activity. Improvements in cardiorespiratory fitness depicted recruits who experienced enough stress to facilitate physiological adaptation, which was reflected by a reduction in HRV during BMT. Monitoring HRV and HRV in relation to interbeat interval length may provide a better tool for determining allostatic load than HRV alone.
心率变异性（HRV）已显示出对防御人员所经历的急性应激源的敏感性。本研究探讨了过夜 HRV 作为防御人员应激负荷的重复测量的适宜性。
在基础军事训练（BMT）的 12 周期间，48 名新兵每天报告睡眠、认知负荷和感知用力情况。每周测量身体活动、主观幸福感和 HRV。使用预测慢波睡眠期间的相邻心跳间隔均方根差的自然对数（Ln RMSSD）和 Ln RMSSD 与心跳间隔比（Ln RMSSD：RRi 比）作为 HRV。在 BMT 的第 2 周和第 8 周，通过 20 米穿梭跑和最大俯卧撑测试评估身体表现，并计算预测的 V̇O 2 峰值。
预测的 V̇O 2 峰值从 42.6 ± 4.5 增加到 48.0 ± 2.7 mL·kg -1 ·min -1 （P < 0.001）。Ln RMSSD 在第 7 周和第 10 周升高，Ln RMSSD：RRi 比在第 10 周高于其他所有周（P < 0.05）。感知用力（F = 9.10，P = 0.003）和主观疲劳（F = 6.97，P = 0.009）的增加，以及 V̇O 2 峰值的降低（F = 7.95，P = 0.009），分别预测 Ln RMSSD 的增加。Ln RMSSD 的最佳预测模型包括感知用力（F = 8.16，P = 0.005）、主观疲劳（F = 8.49，P = 0.004）、睡眠期间的觉醒次数（F = 7.79，P = 0.006）和 V̇O 2 峰值的变化（F = 19.110，P < 0.001）。
HRV 是由新兵对 BMT 工作量的主观反应而不是身体活动的客观测量来预测的。心肺适应能力的提高表明新兵经历了足够的压力来促进生理适应，这反映在 BMT 期间 HRV 的降低。监测 HRV 及其与心跳间隔长度的关系可能比单独监测 HRV 提供更好的工具来确定应激负荷。
