Effects of mild supine exercise during 20 days bed rest on maximal oxygen uptake rate in young humans.
Fourteen sedentary young volunteers performed a maximal exercise test on a bicycle ergometer before, after and eight or nine weeks after 20 days bed rest. They were divided into four groups. They all went through 20 days bed rest; 5 females and 6 males as controls while 3 males performed mild pedaling supine exercise for 30 minutes twice a day. Three other males from the control group started a retraining programme after bed rest performing mild pedaling exercise in the sitting position for an hour a day, 3-4 days a week for eight weeks. VO2max was reduced after bed rest in all groups. In the control group the 6 males decreased VO2max from 2.82 +/- 0.09 1.min-1 before bed rest to 2.42 +/- 0.14 1.min-1 after. The female controls decreased from 2.55 +/- 0.24 1.min-1 to 2.22 +/- 0.23 1.min-1. The exercise regime performed by the three males during bed rest did not prevent a fall in VO2max in that group from 2.76 +/- 0.06 to 2.57 +/- 0.09 1.min-1. The three males who performed bicycle exercise in the recovery period did not attain higher recovery values at 8-9 weeks than the other males. However the 5 female controls did not recover their > 13% loss in VO2max after 8-9 weeks of recovery. Calculation of peak oxygen pulse from VO2max divided by heart rate indicated that these changes in VO2max were caused exclusively by a reduction in stroke volume of the heart, a finding supported by resting echocardiography of left ventricular end-diastolic diameter and stroke volume.(ABSTRACT TRUNCATED AT 250 WORDS)
Kashihara
H
H
Department of Health Administration, Faculty of Medicine, University of Tokyo, Japan.
Haruna
Y
Y
Suzuki
Y
Y
Kawakubo
K
K
Takenaka
K
K
Bonde-Petersen
F
F
Gunji
A
A
D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D012727:Sex Characteristics; D013318:Stroke Volume / Q000502:physiology; D016683:Supine Position; D016277:Ventricular Function, Left / Q000502:physiology