Key result
60-day head-down bedrest significantly impaired the muscle-pump baroreflex, reducing causality from 0.87 at baseline to 0.73 immediately after bedrest.
Why the study?
Mechanisms associated with post-flight orthostatic intolerance, particularly the interaction between cardiovascular and postural functions, remain incompletely understood.
Does 60-day head-down bedrest immobilization impair cardio-postural interactions and muscle-pump baroreflex in healthy young males?
Population
20 healthy young males (35.0 ± 1.7 years)
Comparison
Before vs after 60 days of head down bedrest at 6˚
Follow-up
eight days later (R8)
Authors
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Impaired muscle-pump baroreflex after prolonged bedrest warrants caution during post-immobilization recovery; leaves open whether targeted countermeasures restore cardio-postural function.
RCT (n=19)
Placebo-controlled
Randomized
No
Does 60-day head-down bedrest immobilization impair cardio-postural interactions and muscle-pump baroreflex in healthy young males?
Absolute Event Rate: 0.73% vs 0.87%
p-value: p=<0.001
Prolonged 60-day bedrest immobilization significantly impairs the skeletal muscle-pump baroreflex, contributing to post-flight or post-bedrest orthostatic intolerance.
Xu et al. (2020) conducted an RCT in Healthy (simulating spaceflight-induced fluid shifts) (n=19). 60-day head-down bedrest (HDBR) vs. Baseline (pre-HDBR) was evaluated on Causality of the muscle-pump baroreflex (SBP → EMGimp) (p=<0.001). 60-day head-down bedrest significantly impaired the muscle-pump baroreflex, reducing causality from 0.87 at baseline to 0.73 immediately after bedrest.
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