Effect of Aerobic Exercise Training on Renal Responses to Sodium in Hypertensives

DENGEL, DONALD R.1,2; BROWN, MICHAEL D.3,4; REYNOLDS, THOMAS H. IV3,4; SUPIANO, Mark A.3,4

Medicine & Science in Sports & Exercise: February 2006 - Volume 38 - Issue 2 - pp 217-222
doi: 10.1249/01.mss.0000185106.32139.69
CLINICAL SCIENCES: Clinical Case Studies

Introduction: Aerobic exercise training has been shown to improve cardiovascular function and lower blood pressure (BP) in older adults. The exact mechanism(s) by which aerobic exercise training elicits these changes are unknown; however, it is possible that changes in renal hemodynamics may play a role.

Purpose: The present study was undertaken to examine the effect of aerobic exercise training on renal hemodynamics in older hypertensive individuals.

Methods: Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined by plasma and urinary clearances of 131I-hippuran and 99mTc-DTPA after 8 d of low (20 mEq) and high (200 mEq) Na+ diets in 31 older (63 ± 1 yr), hypertensive (152 ± 2/88 ± 1 mm Hg) individuals at baseline and following 6 months of aerobic exercise training (at 75% V̇O2max, three times a week, 40 min per session).

Results: Following 6 months of aerobic exercise training, a significant increase was seen in maximal aerobic capacity (V̇O2max: 18.3 ± 0.7 vs 20.7 ± 0.7 mL·kg−1·min−1, P = 0.017) as well as a significant decrease in resting systolic (152 ± 2 vs 145 ± 2 mm Hg, P = 0.037) and mean arterial (109 ± 1 vs 105 ± 1 mm Hg, P = 0.021) BP. No significant (P < 0.05) effects were seen of aerobic exercise training on RPF (208.8 ± 12.2 vs 197.1 ± 13.1 mL·min−1·1.73 m−2), GFR (68.9 ± 3.6 vs 69.0 ± 3.9 mL·min−1·1.73 m−2), or filtration fraction (35.3 ± 2.3 vs 37.1 ± 2.4%) on the low Na+ diet or RPF (210.6 ± 12.8 vs 212.1 ± 11.7 mL·min−1·1.73 m−2), GFR (72.9 ± 4.1 vs 77.3 ± 4.3 mL·min−1·1.73 m−2), or filtration fraction (37.1 ± 2.5 vs 37.7 ± 3.0%) on the high Na+ diet.

Conclusions: Our results suggest that changes in renal hemodynamics do not contribute to the reduction in resting BP in older hypertensive persons.

1School of Kinesiology, University of Minnesota, Minneapolis, MN; 2GRECC, Minneapolis Veterans Affairs Medical Center, Minneapolis, MN; 3Department of Internal Medicine, Division of Geriatric Medicine, Ann Arbor, MI; and 4GRECC, Ann Arbor Veterans Affairs Medical Center, Ann Arbor, MI

Address for correspondence: Donald R. Dengel, University of Minnesota, 1900 University Avenue S.E., 110 Cooke Hall, Minneapolis, MN 55455; E-mail: denge001@umn.edu.

Submitted for publication April 2005.

Accepted for publication August 2005.

©2006The American College of Sports Medicine