With NASA’s plans for the human exploration of Mars, astronauts will be exposed to mission durations much longer than current spaceflight missions on the International Space Station. These mission durations will increase the risk for circadian misalignment. Exercise has gained increasing interest as a non-pharmacological aid to entrain the circadian system. To assess the potential of exercise as a countermeasure to mitigate the risk for circadian disorders during spaceflight, we investigated the effects of long-term head-down tilt bed rest (HDBR) with and without exercise on the circadian rhythm of core body temperature. Core body temperature was recorded for 24 h using a rectal probe in sixteen healthy men (age: 30.5 ± 7.5 years (mean ± SD)) after 7 days and 49 days of HDBR. Five participants underwent HDBR only (CTR), five participants underwent HDBR and performed resistive exercises (RE), and six participants underwent HDBR and performed resistive exercises superimposed with vibrations (RVE). The exercise was scheduled three times per week. CTR showed a phase delay of 0.69 h. In contrast, both exercise groups were characterized by a phase advance (0.45 h for RE and 0.45 h for RVE; p = 0.026 for interaction between time and group). These findings suggest that resistive exercise (with or without vibration) may also serve as a countermeasure during spaceflight to mitigate circadian misalignments. The results could also be important for increasing awareness about the role of circadian disorders in long-term bedridden patients.

根据NASA的人类火星探索计划，宇航员的任务持续时间将比目前国际空间站的航天飞行任务更长。这些任务持续时间将增加昼夜节律偏差的风险。作为一种非昼夜节律性生理疗法，锻炼已引起人们越来越多的兴趣。为了评估运动作为缓解航天飞行中昼夜节律障碍风险的对策的潜力，我们调查了长期上下俯卧床卧床休息（HDBR）对有和没有运动对核心体温的昼夜节律的影响。在HDBR治疗7天和49天后，使用直肠探针在16名健康男性（年龄：30.5±7.5年（平均±SD））中记录了24小时的核心体温。五名参与者仅接受了HDBR（CTR），五名参与者进行了HDBR并进行了抵抗性锻炼（RE），六名参与者进行了HDBR并进行了有振动叠加的抵抗性锻炼（RVE）。这项运动计划每周进行三次。点阅率显示0.69小时的相位延迟。相比之下，两个运动组的特征都是阶段提前（RE为0.45小时，RVE为0.45小时； 对于时间与小组之间的互动，p = 0.026）。这些发现表明，抵抗性锻炼（有或没有振动）也可以作为航天飞行中缓解昼夜节律失调的对策。该结果对于提高对长期卧床患者的昼夜节律障碍作用的认识也可能是重要的。