title: Cardiorespiratory responses to exercise after bed rest in men and women.
abstract: The purpose of this study was to compare cardiorespiratory responses of men and women to submaximal and maximal workloads before and after bed rest (BR). Fifteen male college students (19-23 yr) and 8 female nurses (23-34 yr) underwent 14 d and 17 d, respectively of bed rest. The maximal work capacity test was performed in the supine position on a bicycle ergometer just before and immediately after bed rest. The women's maximal O2 uptake (maximal VO2) was 41% lower (P<0.05) than the men's before bed rest and 42% lower (P<0.05) after bed rest. During bed rest the women's maximal VO2 decreased from 2.06 to 1.86 liter/min (-9.7%, P<0.05), and that of the men decreased from 3.52 to 3.20 liter/min (-9.1%, P<0.05). Compared with pre-BR values, after bed rest the maximal ventilatory volume was essentially unchanged in the men (+1.8%) and women (+ 2.3%), but maximal heart rate was elevated from 185 to 193 b/min (+ 4.3%, P<0.05) in the men and from 181 to 187 b/min (3.3%, P<0.05) in the women. Submaximal VO2 was unchanged after bed rest in the men but was significantly reduced in the women; the women's Hct and RBC levels were lower (P<0.05) than comparable male data. Mean corpuscular volume was unchanged in both groups pre- and post-bed rest. It is concluded that the proportional deterioration in maximal VO2 following prolonged bed rest was essentially the same in young men and women.
authors.affiliation: Laboratory of Human Environmental Physiology, Ames Research Center, NASA, Moffett Field, CA 94035, USA.
authors.forename: V A
authors.initials: VA
authors.lastname: Convertino
authors.forename: R W
authors.initials: RW
authors.lastname: Stremel
authors.forename: E M
authors.initials: EM
authors.lastname: Bernauer
authors.forename: J E
authors.initials: JE
authors.lastname: Greenleaf
mesh_terms: D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D018493:Cardiovascular Deconditioning / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008598:Menstruation / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology*; D018474:Weightlessness Simulation / Q000009:adverse effects*