Hypertension, Vol 3, 182-187, Copyright © 1981 by American Heart Association
PS Parfrey, P Wright and JM Ledingham
The effect of stress, in the form of prolonged isometric exercise, on the
circulation and on the renal excretion of sodium and potassium was studied
in 18 patients with mild essential hypertension. Thirteen men and five
women, aged 20 to 50 years with basal diastolic blood pressure (BP) between
90 and 110 mm Hg were matched by age, sex, and race with 18 controls who
had basal diastolic BPs less than 85 mm Hg. After the subjects rested for
90 minutes, basal measurements of pulse rate, BP, and rates of sodium and
potassium excretion were made. The subjects then underwent a 1-hour period
of isometric exercise involving all four limbs in rotation, followed by 5
hours of rest during which the measurements were repeated at half-hourly
intervals for the first 2 hours and at hourly intervals for the last 3
hours. On another day, the subjects were again studied after 1 hour of
resting instead of exercise. Responses of each subject were then expressed
as ratios of changes from the basal values observed on the exercise and
rest days. Changes in systolic and diastolic BP and hart rate were not
significantly different in the hypertensive and control groups. In
hypertensive subjects, the rate of sodium and potassium excretion was
decreased after isometric exercise compared with the rest day, whereas in
normal subjects this response was reversed. For the first 3 hours after
exercise, the cation excretion rate of the hypertensive group was
significantly less than that of the control group. These results indicate
that isometric exercise in mild hypertension induces prolonged renal
retention of both sodium and potassium.
ARTICLES
Prolonged isometric exercise. Part 1: Effect on circulation and on renal excretion of sodium and potassium in mild essential hypertension