Salt restriction lowers blood pressure at rest and during exercise without altering peripheral hemodynamics in hypertensive individuals.

Abstract

Dietary salt restriction is a well-established approach to lower blood pressure and reduce cardiovascular disease risk in hypertensive individuals. However, little is currently known regarding the effects of salt restriction on central and peripheral hemodynamic responses to exercise in those with hypertension. Therefore, this study sought to determine the impact of salt restriction on the central and peripheral hemodynamic responses to static-intermittent handgrip (HG) and dynamic single-leg knee extension (KE) exercise in individuals with hypertension. Twenty-two subjects (14 men and 8 women, 51 ± 10 yr, 173 ± 11 cm, 99 ± 23 kg) forewent their antihypertensive medication use for at least 2 wk before embarking on a 5-day liberal salt (LS: 200 mmol/day) diet followed by a 5-day restricted salt (RS: 10 mmol/day) diet. Subjects were studied at rest and during static intermittent HG exercise at 15, 30, and 45% of maximal voluntary contraction and KE exercise at 40, 60, and 80% of maximum KE work rate. Salt restriction lowered resting systolic blood pressure (supine: -12 ± 12 mmHg, seated: -17 ± 12 mmHg) and diastolic blood pressure (supine: -3 ± 9 mmHg, seated: -5 ± 7 mmHg, P < 0.05). Despite an ~8 mmHg lower mean arterial blood pressure during both HG and KE exercise following salt restriction, neither central nor peripheral hemodynamics were altered. Therefore, salt restriction can lower blood pressure during exercise in subjects with hypertension, reducing the risk of cardiovascular events, without impacting central and peripheral hemodynamics during either arm or leg exercise.NEW & NOTEWORTHY This is the first study to examine the potential blood pressure-lowering benefit of a salt-restrictive diet in individuals with hypertension without any deleterious effects of exercising blood flow. While mean arterial pressure decreased by ~8 mmHg following salt restriction, these findings provide evidence for salt restriction to provide protective effects of reducing blood pressure without inhibiting central or peripheral hemodynamics required to sustain arm or leg exercise in subjects with hypertension.