A plethora of evidence exists supporting that structured aerobic exercise or activities that increase cardiorespiratory fitness (CRF) lower resting blood pressure (BP) in patients with hypertension (HTN). Relatively few studies have assessed the effects of anaerobic or resistance exercise on BP. Thus, its role in managing HTN is not defined. Also, possible risks related with exercise in hypertensive patients have not been adequately addressed.
In addition to lowering BP, CRF attenuates the incidence of HTN. A substantial part of the age-related progression to HTN is not an inevitable outcome of aging as once thought, but a consequence of lifestyle characterized by high-fat/salt diets and physical inactivity. In our studies, the CRF-HTN association was inverse and graded. The relative risk for developing HTN was 72% higher for low-fit compared to fit individuals. We also found an independent, inverse and graded association between CRF and the risk for developing congestive heart failure (CHF). For every 1-MET increase in exercise capacity the risk for CHF was 16% lower (HR = 0.84; CI: 0.83–0.86) in 8,725 US veterans. Compared to the Least-Fit category, the risk was progressively lower, ranging from 32% for moderate fit to 70% for those in the highest fitness category. CRF and mortality risk association was also inverse and graded in hypertensive patients, independent of age, body weight, medications and additional risk factors.
Available evidence supports that dynamic resistance exercise is less effective in lowering BP than aerobic exercise. Due to a considerable degree of inconsistency in the findings of such studies, and the risk for an exaggerated BP response, resistance training exercise prescription for hypertensive patients is premature. Hypertensive patients interested in resistance training should be advised to avoid high-resistance training and prefer low-resistance, high repetitions (15–20) exercises. To avoid an exaggerated BP response, patients should be advised against holding their breath during physical exertion.
The mechanisms involved in exercise-related effects on BP are based on the principle that when a biological system is challenged repeatedly beyond its present capacity this system will undergo specific adaptation designed to overcome the challenge. Accordingly, the shear stress generated by the increased blood flow during exercise provides the stimulus for enhanced nitric oxide release, and improved endothelial function, ultimately leading to a reduction in vascular resistance and mean arterial pressure.
An elusive threshold exists for exercise intensity, duration, frequency and volume for the exercise-related effects on BP. Brisk walk most days of the week, 20–40 minutes per session meets the requirements for BP reduction. Running is not required and may even increase risk for injury.