Chronic Endurance Exercise Training Offsets the Age-related Attenuation in Contraction-Induced Rapid Vasodilation

Aging is associated with attenuated contraction-induced rapid onset vasodilation (ROV). We sought to examine whether chronic exercise training would improve ROV in older adults. Additionally, we examined whether a relationship between cardiorespiratory fitness and ROV exists in young and older adults. Chronically exercise trained older adults (n=16; 66±2yr) performed single muscle contractions in the forearm and leg at various intensities. Brachial and femoral artery diameter and blood velocity were measured using Doppler ultrasound. Vascular conductance (VC) was calculated as the quotient of blood flow (ml·min^-1) and mean arterial pressure (mmHg). These data were compared with our previously published work from an identical protocol in 16 older untrained (66±1yr) and 14 young (23±1yr) adults. Peak (VC_peak) and total vasodilator (VC_total) responses were greater in trained compared to untrained older adults across leg exercise intensities (P<0.05). There were no differences in responses between trained older and young adults in the arm or leg at any exercise intensity (P>0.05). Comparison of VC_peak in a subset of subjects at an absolute workload in the leg revealed that trained older adults exhibited augmented responses relative to untrained older adults. Exercise capacity (VO₂peak) was associated with VC_peak and VC_totall across arm (r=0.59-0.64) and leg exercise intensities (r=0.55-0.68; P<0.05) in older adults. Our data demonstrate that 1) chronic exercise training improves ROV in the arm and leg of trained older adults, such that age-related differences in ROV are abolished; and 2) VO₂peak is associated with VC_peak responses in both limbs of older adults.

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