Relationship between Exercise Capacity and Rapid Vasodilator Responses to Single Skeletal Muscle Contractions in Young and Older Adults

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We examined the relationship between exercise capacity (VO2peak) and contraction‐induced rapid vasodilation in skeletal muscle and whether the potential relationship varied by limb (leg vs. arm) and/or age (young vs. older). 33subjects (14 young, 23±1yr; 19 older, 65±1yr) performed single muscle contractions at 10, 20 and 40% of maximum for handgrip and 20, 40, and 60% work rate maximum for knee extension. Blood flow (ml/min) was measured using Doppler ultrasound and vascular conductance was calculated from blood flow and blood pressure (mmHg) and normalized for muscle mass (kg). VO2peak was related to peak contraction‐induced vasodilation in the arm (r=0.32‐0.37, P=0.04‐0.07) and leg (r=0.48 – 0.60, P<0.01) across intensities for all individuals included in the study. However, when separated by age group VO2peak was not related to rapid vasodilation in the arm within either group or in the leg of the young adults. Conversely, older adults demonstrated a strong relationship between VO2peak and peak rapid vasodilation in the leg at the 20% (r=0.68), 40% (r=0.65), and 60% (r=0.75) intensity (P<0.01 for all). Our data suggest that a relationship between VO2peak and contraction‐induced rapid vasodilation exists in the leg of older adults. These relationships may provide insight into the positive effects of exercise training on vascular function and skeletal muscle perfusion in older adults.Funded by NIH HL‐105467