Abstract：
BACKGROUND: Measuring cortisol during military training offers insights into physiological responses to stress. We attempted precisely timed, cortisol awakening response (CAR) and pre-sleep cortisol (PSC), and diurnal slope (peak morning minus evening cortisol), during a British Army exercise. We aimed to understand cortisol dynamics and evaluate the feasibility of CAR and PSC in this environment.
METHODS: Setting: high-intensity, 10-day infantry exercise. Participants: regular infantry soldiers exercising (EX, n=25) or headquarters-based (HQ, n=6). Participants undertook PSC and WAKE and WAKE+30 min samples after 1-2 days, 5-6 days and 9-10 days. Wrist-worn GENEActiv accelerometers were used to assess sleep duration in EX only. Samples taken ±15 min from prespecified time points were deemed adherent. Validated questionnaires were used to measure resilience and perceived stress. Cortisol and cortisone were measured simultaneously by liquid chromatography tandem mass spectrometry.
RESULTS: From adherent participants\' samples, CAR was positive and tended to decrease as the exercise progressed. From all available data, HQ demonstrated greater diurnal slope than EX (F=7.68, p=0.02), reflecting higher morning cortisol (F=4.72, p=0.038) and lower PSC (p=0.04). No differences were seen in cortisol:cortisone ratio. 26.1% of CAR samples were adherent, with moderately strong associations between adherence and stress (r=0.41, p=0.009) but no association between adherence and day of exercise (χ2=0.27, p=0.8), sleep duration (r=-0.112, p=0.43) or resilience (r=-0.79, p=0.75). Test-retest reliability ratings for CAR were Cronbach\'s α of 0.48, -11.7 and 0.34 for the beginning, middle and end of the exercise, respectively.
CONCLUSIONS: We observed a reduction in morning cortisol and decreased diurnal slope during a high-intensity military exercise, compared with the HQ comparator cohort in whom diurnal slope was preserved. A carefully timed CAR was not feasible in this setting.
METHODS: Setting: high-intensity, 10-day infantry exercise. Participants: regular infantry soldiers exercising (EX, n=25) or headquarters-based (HQ, n=6). Participants undertook PSC and WAKE and WAKE+30 min samples after 1-2 days, 5-6 days and 9-10 days. Wrist-worn GENEActiv accelerometers were used to assess sleep duration in EX only. Samples taken ±15 min from prespecified time points were deemed adherent. Validated questionnaires were used to measure resilience and perceived stress. Cortisol and cortisone were measured simultaneously by liquid chromatography tandem mass spectrometry.
RESULTS: From adherent participants\' samples, CAR was positive and tended to decrease as the exercise progressed. From all available data, HQ demonstrated greater diurnal slope than EX (F=7.68, p=0.02), reflecting higher morning cortisol (F=4.72, p=0.038) and lower PSC (p=0.04). No differences were seen in cortisol:cortisone ratio. 26.1% of CAR samples were adherent, with moderately strong associations between adherence and stress (r=0.41, p=0.009) but no association between adherence and day of exercise (χ2=0.27, p=0.8), sleep duration (r=-0.112, p=0.43) or resilience (r=-0.79, p=0.75). Test-retest reliability ratings for CAR were Cronbach\'s α of 0.48, -11.7 and 0.34 for the beginning, middle and end of the exercise, respectively.
CONCLUSIONS: We observed a reduction in morning cortisol and decreased diurnal slope during a high-intensity military exercise, compared with the HQ comparator cohort in whom diurnal slope was preserved. A carefully timed CAR was not feasible in this setting.
摘要：
背景：在军事训练期间测量皮质醇提供了对压力的生理反应的见解。我们试图精确计时，皮质醇觉醒反应（CAR）和睡前皮质醇（PSC），和昼夜斜率（早晨高峰减去晚上皮质醇），在英国陆军演习中。我们旨在了解皮质醇动力学并评估CAR和PSC在这种环境中的可行性。
方法：设置：高强度，为期10天的步兵演习。参与者：常规步兵练习（EX，n=25)或总部(总部，n=6)。参与者在1-2天后进行PSC和WAKE和WAKE+30分钟样本，5-6天和9-10天。腕上佩戴的GENEActiv加速度计仅用于评估EX的睡眠持续时间。从预先指定的时间点取±15分钟的样品被认为是粘附的。使用经过验证的问卷来测量弹性和感知压力。采用液相色谱串联质谱法同时测定皮质醇和可的松。
结果：来自坚持参与者的样本，CAR是阳性的，并且随着运动的进行而趋于减少。从所有可用数据来看，HQ表现出比EX更大的日斜率(F=7.68，p=0.02)，反映较高的早晨皮质醇（F=4.72，p=0.038）和较低的PSC（p=0.04）。皮质醇：可的松比例没有差异。26.1%的汽车样品是粘附的，依从性和压力之间具有中等强度的相关性（r=0.41，p=0.009），但依从性和锻炼日之间没有相关性（χ2=0.27，p=0.8），睡眠持续时间（r=-0.112，p=0.43）或弹性（r=-0.79，p=0.75）。汽车的重测可靠性评级为Cronbach'sα，最初为0.48，-11.7和0.34，练习的中间和结束，分别。
结论：我们观察到在高强度军事演习中，早晨皮质醇减少，昼夜斜率减少，与保留昼夜斜率的总部比较队列相比。在此设置中,仔细定时的CAR是不可行的。
方法：设置：高强度，为期10天的步兵演习。参与者：常规步兵练习（EX，n=25)或总部(总部，n=6)。参与者在1-2天后进行PSC和WAKE和WAKE+30分钟样本，5-6天和9-10天。腕上佩戴的GENEActiv加速度计仅用于评估EX的睡眠持续时间。从预先指定的时间点取±15分钟的样品被认为是粘附的。使用经过验证的问卷来测量弹性和感知压力。采用液相色谱串联质谱法同时测定皮质醇和可的松。
结果：来自坚持参与者的样本，CAR是阳性的，并且随着运动的进行而趋于减少。从所有可用数据来看，HQ表现出比EX更大的日斜率(F=7.68，p=0.02)，反映较高的早晨皮质醇（F=4.72，p=0.038）和较低的PSC（p=0.04）。皮质醇：可的松比例没有差异。26.1%的汽车样品是粘附的，依从性和压力之间具有中等强度的相关性（r=0.41，p=0.009），但依从性和锻炼日之间没有相关性（χ2=0.27，p=0.8），睡眠持续时间（r=-0.112，p=0.43）或弹性（r=-0.79，p=0.75）。汽车的重测可靠性评级为Cronbach'sα，最初为0.48，-11.7和0.34，练习的中间和结束，分别。
结论：我们观察到在高强度军事演习中，早晨皮质醇减少，昼夜斜率减少，与保留昼夜斜率的总部比较队列相比。在此设置中,仔细定时的CAR是不可行的。
