Indices of orthostatic intolerance following 10 days of bedrest in healthy, older men and women

TL;DRAbstract

Moving from a supine to standing position (orthostasis) requires multiple cardiovascular and autonomic adjustments to maintain blood pressure and cerebral perfusion. We examined cardiovascular and catecholamine responses to a standardized orthostatic challenge before and after 10 d of bedrest in healthy men and women ( n = 24) aged 55 – 80 y. The orthostatic test involved measurements of heart rate, blood pressure, and serum catecholamines during 10 min of supine rest followed by 10 min of standing. A test was terminated if the subject experienced any orthostatic symptoms (e.g. lightheadedness). Two subjects were symptomatic during pre‐bedrest testing, while 5 subjects were symptomatic post‐bedrest. Heart rate during the standing portion of the test was higher than the supine value; the difference between standing and supine values was significantly greater at post‐ vs. pre‐bedrest (22.3 ± 9.7 vs. 14.1 ± 15.8 bpm, respectively, p = 0.01). The difference between standing and supine seru

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