Blunted leg vasodilation during isolated quadriceps exercise in healthy older women

Abstract

Purpose. To examine the influence of age on leg blood flow responses in women utilizing an exercise modality in which central (cardiac output) limitations to blood flow are minimized. Methods. Femoral artery blood flow (FBF; estimated from Doppler-ultrasound derived measurements of diameter and blood velocity) was measured at rest and during incremental (3W increases) single knee-extensor exercise to exhaustion in 9 young (Y: 22 ± 1 yrs) and 14 older (O: 68 ± 1 yrs) healthy women. Beat-by-beat femoral vascular conductance (FVC) was calculated as the quotient of FBF and mean arterial pressure (MAP) at rest and during the last minute of each 3 minute workload. Data (Y vs O) are expressed as mean ± S.E.M. Results. At rest, FBF and FVC were lower in O compared to Y (310 ± 64 vs 157 ± 30 mL/min and 4.1 ± 0.8 vs 2.1 ± 0.5 mL/min/mmHg; p < 0.01) while MAP was not significantly different between groups (77 ± 3 vs 80 ± 3 mmHg; p = 0.49). At every workload, FBF and FVC were lower in O such that peak FBF and FVC (observed at ~ 24–27 W) were reduced in O by ~ 40% (1809 ± 157 vs 1089 ± 61 mL/min and 19.3 ± 1.8 vs 10.5 ± 0.8 mL/min/mmHg; p < 0.01) despite significantly (p < 0.05) augmented MAP exhibited by O at workloads > 6W. Summary. These findings provide the most definitive evidence to date supporting a peripheral limit to vasodilation in the lower limb vasculature of healthy aging women. Research supported by NIH award R01-AG-18246 (DNP) and NIA Grant #T32 AG00048 (BAP).