Effect of aerobic exercise training on blood pressure sensitivity to dietary sodium in older hypertensives

Although aerobic exercise training has been shown to lower blood pressure (BP) in older adults, its effect on BP sensitivity to dietary sodium (Na⁺) is unknown. Therefore, the present study was undertaken to examine the effect of aerobic exercise training on BP sensitivity to dietary Na⁺ in older hypertensive individuals. Blood pressure was measured after 8 days of low (20 mEq) and high (200 mEq) Na⁺ diets in 31 older (63 ± 7 years, mean±standard deviation), hypertensive (152 ± 11/ 88 ± 5 mm Hg) individuals at baseline and following 6 months of aerobic exercise training (at 75% VO₂max, 3 times/week, 40 min/session). Subjects were grouped on the basis of the difference in mean arterial BP (MAP) between diets (Na⁺ sensitive: ≥5 mm Hg increase in MAP on high Na⁺, n = 20; Na⁺ resistant: <5 mm Hg increase in MAP on the high Na⁺ diet, n=11). Following 6 months of aerobic exercise training, there was a significant increase in maximal aerobic capacity (VO₂max: 18.3 ± 3.8 vs 20.7 ± 4.2 ml/kg/min, P < 0.017). Aerobic exercise training had a significant (P = 0.02) effect on Na⁺ sensitivity status, with the proportion of Na⁺-resistant individuals increasing from 35% at baseline to 61% following the 6-month aerobic exercise training programme. This study demonstrates the importance of physical activity on BP sensitivity to dietary Na⁺.