Key result
Long-duration Antarctic overwintering was associated with a gradual reduction in vagal tone and a progressive shift toward sympathetic predominance (P=0.020 for log LF/HF), which was particularly pronounced in women.
Why the study?
Long-duration Antarctic expeditions involve isolation, confinement, and extreme environments, but the time course of cardiac autonomic modulation during these conditions required characterization.
Does a long-duration Antarctic overwintering expedition alter cardiac autonomic modulation in healthy crewmembers?
Observational (n=25)
No
Does a long-duration Antarctic overwintering expedition alter cardiac autonomic modulation in healthy crewmembers?
p-value: p=0.020
Long-duration isolation and confinement during Antarctic overwintering induces a progressive depression of cardio-vagal tone and a shift toward sympathetic predominance, which is particularly pronounced in women.
May warrant autonomic monitoring in isolated missions; leaves open effects on cardiovascular outcomes in space analogs.
Long-duration Antarctic expeditions are characterized by isolation, confinement, and extreme environments. Here we describe the time course of cardiac autonomic modulation assessed by heart rate variability (HRV) during 14-month expeditions at the German Neumayer III station in Antarctica. Heart rate recordings were acquired in supine position in the morning at rest once before the expedition (baseline) and monthly during the expedition from February to October. The total set comprised twenty-five healthy crewmembers (n = 15 men, 38 ± 6 yrs, n = 10 women, 32 ± 6 yrs, mean ± SD). High frequency (HF) power and the ratio of low to high frequency power (LF/HF) were used as indices of vagal modulation and sympathovagal balance. HF power adjusted for baseline differences decreased significantly during the expedition, indicating a gradual reduction in vagal tone. LF/HF powers ratio progressively shifted toward a sympathetic predominance reaching statistical significance in the final trimester (August to October) relative to the first trimester (February to April). This effect was particularly pronounced in women. The depression of cardio-vagal tone and the shift toward a sympathetic predominance observed throughout the overwintering suggest a long-term cardiac autonomic modulation in response to isolation and confinement during Antartic overwintering.
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Maggioni et al. (2020) conducted an observational in Healthy (Isolation and Confinement) (n=25). Antarctic overwintering (isolation and confinement) vs. Pre-expedition baseline was evaluated on Time course of cardiac autonomic modulation assessed by heart rate variability (log HF and log LF/HF) (p=0.020). Long-duration Antarctic overwintering was associated with a gradual reduction in vagal tone and a progressive shift toward sympathetic predominance (P=0.020 for log LF/HF), which was particularly pronounced in women.
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