Primary outcomes (HRV indexes).

Fatigue is a multidimensional phenomenon. Although psychological tests can be used to evaluate subjective fatigue, an objective measurement of fatigue is needed to evaluate mental, physical, and occupational health and inform appropriate interventions. Heart rate variability (HRV) has emerged as a potential candidate for assessing objective mental fatigue; however, its effectiveness and safety remain inconclusive. To address these, we conducted a single-center, randomized trial to compare the efficacy and safety of HRV with subjective psychological tests for evaluating mental fatigue. Participants aged 20 to 65 years who had received annual health check-ups and had been found to have no health concerns were included in this study. We compared HRV indexes after performing a calculation task with a control group that rested. The primary outcomes were HRV indexes as recorded by wearable electrocardiography after an intervention consisting of a calculation task. Subjective measures (visual analog scale [VAS] for fatigue and Profile of Mood States 2nd Edition [POMS2]) were evaluated as secondary outcomes. One hundred forty participants were randomized into a calculation task and control groups. Participants who performed the calculation task had a lower square root of the mean squared differences between successive RR intervals (RMSSD), absolute power in the high-frequency band, and standard deviation of Poincaré plot. In psychological tests, participants who performed the calculation task demonstrated significantly higher scores on the VAS for fatigue and POMS2. Multiple comparisons of RMSSD from HRV indexes, VAS for fatigue, and total mood disturbance from POMS2 revealed that RMSSD and VAS for fatigue were significant indicators associated with the calculation task. On the other hand, the vectors of HRV indexes and psychological tests differed based on primary component analysis. We identified RMSSD, an objective index, and VAS for fatigue, a subjective index, as significantly related to mental fatigue.

疲劳是一种多维度现象。尽管可通过心理测试评估主观疲劳，但为评估心理、生理及职业健康状态并指导合理干预，仍需开展疲劳的客观测量。心率变异性（Heart Rate Variability, HRV）已成为评估客观心理疲劳的潜在候选指标，但其有效性与安全性尚未明确。
为解决上述问题，本研究开展单中心随机试验，对比HRV与主观心理测试在评估心理疲劳方面的有效性及安全性。本研究纳入年龄20~65岁、曾接受年度健康体检且未发现健康异常的受试者。研究将受试者随机分为计算任务组与静息对照组，比较两组完成对应任务后的HRV指标差异。主要结局指标为：经计算任务干预后，通过可穿戴心电图设备记录的HRV相关指标；次要结局指标为主观测评指标，包括疲劳视觉模拟量表（Visual Analog Scale, VAS）及心境状态量表第二版（Profile of Mood States 2nd Edition, POMS2）。
本研究共纳入140名受试者并完成随机分组。完成计算任务的受试者，其相邻RR间期差值均方根（Root Mean Square of Successive Differences between RR Intervals, RMSSD）、高频段绝对功率及庞加莱图标准差均显著降低。在心理测试中，计算任务组受试者的疲劳VAS评分及POMS2评分均显著升高。
对HRV指标中的RMSSD、疲劳VAS评分及POMS2总心境紊乱得分进行多重比较后发现，RMSSD与疲劳VAS评分均为与计算任务显著相关的指标。此外，主成分分析结果显示，HRV指标与心理测试的向量存在差异。
本研究确定，客观指标RMSSD与主观指标疲劳VAS评分均与心理疲劳显著相关。