Joel D Trinity, Gwenael Layec, Russell S Richardson, Corey R Hart
An exaggerated blood pressure (BP) response to exercise has been linked to cardiovascular disease (CVD), but little is known about the impact of age and sex on this response. Therefore, this study examined the hemodynamic and skeletal muscle metabolic response to dynamic plantar flexion exercise, at 40% of WRmax, in 40 physical activity-matched young (n=20, 23±1 yr) and old (n=20, 73±2 yr), equally distributed, male and female subjects. Central hemodynamics and BP (finometer), popliteal artery (PA) blood flow (Doppler ultrasound), and skeletal muscle metabolism (phosphorous magnetic resonance spectroscopy, (31)P-MRS) were measured during 5 mins of plantar flexion exercise. PA blood flow and high energy phosphate responses to exercise were not affected by age or sex, while aging, independent of sex, attenuated the stroke volume (SV) and cardiac output (CO) responses. Systolic BP (SBP) and mean arterial pressure (MAP) responses were exaggerated in the old women (Δ42±4 mmHg, Δ28±3 mmHg, respectively), with all other groups exhibiting similar increases in SBP (old men: Δ27±8; young men: Δ27±3; young women: Δ22±3 mmHg) and MAP (old men: Δ15±4; young men: Δ19±2; young women: Δ17±2 mmHg). Interestingly, the exercise-induced change in systemic vascular resistance (SVR) in the old women (∆0.8±1.0 mmHg/L/min) was augmented compared to the young women and the young and old men (∆ -2.8±0.5, ∆ -1.6±0.6, ∆ -3.18±1.4 mmHg/L/min, respectively, p < 0.05). Thus, in combination, advancing age and female sex results in an exaggerated BP response to exercise, likely the result of a failure to reduce SVR.