Key result
Sympathetic stimulation via cold-pressor test reduced contraction-induced rapid vasodilation similarly in older and young adults (-22% vs -25% at 20% WRmax; P=0.42-0.55).
Why the study?
Does sympathetic nervous system activation via cold-pressor test reduce contraction-induced rapid vasodilation in the leg differently in young versus older adults?
Cross-Sectional (n=25)
Does sympathetic nervous system activation via cold-pressor test reduce contraction-induced rapid vasodilation in the leg differently in young versus older adults?
Sympathetic vasoconstriction reduces contraction-induced rapid onset vasodilation in the leg similarly in young and older adults, suggesting it does not fully explain age-related attenuations in this response.
Sympathetic inhibition of rapid vasodilation preserved across age; leaves open relevance to age-related exercise intolerance in clinical populations.
Contraction-induced rapid vasodilation is attenuated similarly in the upper and lower limbs of older adults. In the forearm, this attenuation is in part due to a greater sympathetic vasoconstriction. We examined whether the age-related reduction in contraction-induced vasodilation in the leg is also due to a sympathetic vasoconstrictive mechanism. Thirteen young (24 ± 1 yr) and twelve older adults (67 ± 1 yr) performed single-leg knee extension at 20 and 40% of work-rate maximum (WR max ) during control and cold-pressor test (CPT) conditions. Femoral artery diameter and blood velocity were measured using Doppler ultrasound. Vascular conductance (VC; ml·min −1 ·mmHg −1 ) was calculated using blood flow (ml/min) and mean arterial pressure (mmHg). Peak (ΔVC from baseline) and total VC were blunted in older adults during control conditions across exercise intensities ( P < 0.05). Peak and total VC were reduced during CPT in both age groups across exercise intensities ( P < 0.05). The relative change (i.e., %reduction; CPT vs. control) in peak (−25 ± 5 vs. −22 ± 4% at 20% WR max ; and −21 ± 6 vs. −27 ± 5% at 40% WR max ; P = 0.42–0.55) and total VC (−28 ± 5 vs. −36 ± 6% at 20% WR max ; and −22 ± 8 vs. −33 ± 5% at 40% WR max ; P = 0.23–0.34) were similar between young and older adults. When matched for absolute workload (~10 W), age differences persisted in peak VC ( P < 0.05) under both conditions, with similar relative changes in peak and total VC during CPT. Our data suggest that 1) sympathetic stimulation reduces contraction-induced rapid vasodilation in the leg of young and older adults similarly; and 2) enhanced sympathetic vasoconstriction does not fully explain age-related differences in contraction-induced vasodilation within the leg. NEW & NOTEWORTHY Aging is associated with attenuated contraction-induced rapid onset vasodilation (ROV). Within the forearm, this attenuation is partially due to enhanced sympathetic vasoconstriction. In the current study, we found that sympathetic vasoconstriction reduces contraction-induced ROV within the leg of both young and older adults, with the magnitude of change being similar between age groups. Our current results suggest that age-related attenuations in contraction-induced ROV within the leg are not fully explained by a sympathetic vasoconstrictor mechanism.
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Hughes et al. (2017) reported a cross-sectional. Older age vs. Young age was evaluated on Relative reduction in peak vascular conductance during cold-pressor test vs control at 20% WRmax (p=0.42-0.55). Sympathetic stimulation via cold-pressor test reduced contraction-induced rapid vasodilation similarly in older and young adults (-22% vs -25% at 20% WRmax; P=0.42-0.55).
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