Hemodynamic Response to Acute and Chronic Exercise in Obese and Lean Prehypertensive Men

Abstract

PURPOSE: Approximately 7.1 million deaths worldwide are ascribed to hypertension (HTN). Those with HTN who fit the lean body phenotype are characterized by mechanistically different HTN compared to an obese HTN phenotype. The purpose of this study was to assess whether body phenotype influences blood pressure (BP) response following both acute and chronic exercise. METHODS: Obese (body mass index (BMI)>30 kg/m2) and normal weight (BMI < 25 kg/m2) men with pre-hypertension (PHTN) (systolic BP (SBP) 120-139 or diastolic BP (DBP) 80-89 mmHg) were asked to participate in a two phase trial. Phase 1 assessed differences in post-exercise hypotension between groups in response to an acute exercise bout. Phase 2 consisted of a two-week aerobic exercise intervention at 65-70% of heart rate (HR) max on a cycle ergometer. Primary outcome measures were; brachial BP, central BP, cardiac output (CO), and systemic vascular resistance (SVR) measured acutely after one exercise session and following two-weeks of training. RESULTS: There were no baseline resting brachial BP (126 ± 7 mmHg vs. 126 ± 5 mmHg, P=0.976), central BP (110 ± 5 mmHg vs. 113 ± 6, P=0.123), age (24 ± 4 yr vs. 25 ± 4 yr, P = 0.547), or VO2 peak (2.9 ± .4 l.min-1 vs. 3.2 ± .7 l.min-1, P=0.248) differences between Lean and Obese. At rest, obese PHTN had greater CO compared to lean PHTN (6.3 ± 1 vs 4.7 ± 1 L/min, P = 0.005) and decreased SVR compared to lean PHTN (1218 ± 263 vs 1606 ± 444 Dyn.s/cm5, P = 0.003). Lean PHTN saw a 3 mmHg reduction on both brachial and central SBP (P < 0.05) in response to acute exercise, while obese PHTN witnessed a significant 4 mmHg increased brachial and 3 mmHg increased central SBP (P < 0.05). SVR decreased greater following acute exercise in lean PHTN compared to obese PHTN (224 dyn.s/cm5 vs. 75 dyn.s/cm5, P<0.001). Chronic training evoked a 4 mmHg reduction in brachial SBP and 3 mmHg reduction for central SBP for lean PHTN with no change in obese PHTN. Lean BP reduction in response to training was accompanied by a significant SVR reduction of 169 dyn.s/cm5 (P<0.05), while obese experienced a significant increased SVR following training (95 dyn.s/cm5 P<0.05). CONCLUSION: Body phenotype may play a significant role in relation to the efficacy of aerobic exercise on BP reduction.