Objective

Body mass (BM) loss and body composition (BC) changes threaten astronauts’ health and mission success. However, the energetic contribution of the exercise countermeasure to these changes has never been investigated during long-term missions. We studied energy balance and BC in astronauts during 6-month missions onboard the International Space Station.

Methods

Before and after at least 3 months in space, BM, BC, total and activity energy expenditure (TEE and AEE) were measured using the doubly labeled water method in 11 astronauts (2011–2017). Physical activity (PA) was assessed by the SensewearPro® activity-device.

Results

Three-month spaceflight decreased BM (− 1.20 kg [SE 0.5]; P = 0.04), mainly due to non-significant fat-free mass loss (FFM; − 0.94 kg [0.59]). The decrease in walking time (− 63.2 min/day [11.5]; P < 0.001) from preflight was compensated by increases in non-ambulatory activities (+ 64.8 min/day [18.8]; P < 0.01). Average TEE was unaffected but a large interindividual variability was noted. Astronauts were stratified into those who maintained (stable_TEE; n = 6) and those who decreased (decreased_TEE; n = 5) TEE and AEE compared to preflight data. Although both groups lost similar BM, FFM was maintained and FM reduced in stable_TEE astronauts, while FFM decreased and FM increased in decreased_TEE astronauts (estimated between-group-difference (EGD) in ΔFFMindex [FFMI] 0.87 kg/m², 95% CI + 0.32 to + 1.41; P = 0.01, ΔFMindex [FMI] − 1.09 kg/m², 95% CI − 2.06 to − 0.11 kg/m²; P = 0.03). The stable_TEE group had higher baseline FFMI, and greater baseline and inflight vigorous PA than the decreased_TEE group (P < 0.05 for all). ΔFMI and ΔFFMI were respectively negatively and positively associated with both ΔTEE and ΔAEE.

Conclusion

Both ground fitness and inflight overall PA are associated with spaceflight-induced TEE and BC changes and thus energy requirements. New instruments are needed to measure real-time individual changes in inflight energy balance components.

中文翻译：

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运动对国际空间站宇航员能量消耗和身体成分的影响：星际旅行的注意事项

客观的

体重 (BM) 损失和身体成分 (BC) 变化威胁着宇航员的健康和任务成功。然而，在长期任务中从未研究过演习对策对这些变化的积极贡献。我们在国际空间站执行为期 6 个月的任务期间研究了宇航员的能量平衡和 BC。

方法

在太空至少 3 个月前后，使用双标水法测量了 11 名宇航员 (2011-2017) 的 BM、BC、总能量消耗和活动能量消耗（TEE 和 AEE）。身体活动 (PA) 通过 SensewearPro® 活动设备进行评估。

结果

三个月的太空飞行降低了 BM（− 1.20 kg [SE 0.5]；P  = 0.04），主要是由于非显着的无脂肪质量损失（FFM；− 0.94 kg [0.59]）。飞行前减少的步行时间（- 63.2 分钟/天 [11.5]；P  < 0.001）被非走动活动的增加所补偿（+ 64.8 分钟/天 [18.8]；P  < 0.01）。平均 TEE 未受影响，但注意到个体间存在较大差异。宇航员被分为维持 (stable_TEE; n  = 6) 和减少 (decreased_TEE; n ) 的人 = 5) TEE 和 AEE 与飞行前数据的比较。尽管两组失去了相似的 BM，但在 stable_TEE 宇航员中 FFM 得以维持且 FM 降低，而在 decreased_TEE 宇航员中 FFM 降低且 FM 增加（ΔFFMindex [FFMI] 中的组间差异 (EGD) 估计为 0.87 kg/m 2，95 ^% CI + 0.32 至 + 1.41；P  = 0.01，ΔFMindex [FMI] − 1.09 kg/m ²，95% CI − 2.06 至 − 0.11 kg/m ²；P  = 0.03)。与降低的_TEE 组相比，稳定的_TEE 组具有更高的基线 FFMI，以及更高的基线和飞行中剧烈 PA（所有P  < 0.05）。ΔFMI 和 ΔFFMI 分别与 ΔTEE 和 ΔAEE 呈负相关和正相关。

结论

地面健身和机上整体 PA 都与航天引起的 TEE 和 BC 变化以及能量需求相关。需要新仪器来测量飞行中能量平衡组件的实时个体变化。