Mild- to moderate-intensity dynamic leg exercise in middle-aged subjects elicited a larger fall in MSNA burst incidence compared to young subjects (-19 vs -11 bursts/100 heart beats; P=0.01).
Observational (n=36)
Does advancing age alter the muscle sympathetic nerve activity and blood pressure response to mild-to-moderate dynamic leg exercise in healthy humans?
Contrary to prior hypotheses, advancing age is associated with a greater rise in systolic blood pressure and a larger fall in muscle sympathetic nerve activity during mild-to-moderate dynamic leg exercise.
Absolute Event Rate: -19% vs -11%
p-value: p=0.01
Muscle sympathetic nerve activity (MSNA) at rest increases with age. However, the influence of age on MSNA recorded during dynamic leg exercise is unknown. We tested the hypothesis that aging attenuates the sympatho-inhibitory response observed in young subjects performing mild to moderate 1-leg cycling. After predetermining peak oxygen uptake, we compared contra-lateral fibular nerve MSNA during 2 min each of mild (unloaded) and moderate (30%-40% of the work rate at peak oxygen uptake, halved for single leg) 1-leg cycling in 18 young (age, 23 ± 1 years (mean ± SE)) and 18 middle-aged (age, 57 ± 2 years) sex-matched healthy subjects. Mean height, weight, resting heart rate, systolic blood pressure, and percent predicted peak oxygen uptake were similar between groups. Middle-aged subjects had higher resting MSNA burst frequency and incidence (P < 0.001) and diastolic blood pressure (P = 0.04). During moderate 1-leg cycling, older subjects' systolic blood pressure increased more (+21 ± 5 vs. +10 ± 1 mm Hg; P = 0.02) and their fall in MSNA burst incidence was amplified (-19 ± 2 vs. -11 ± 2 bursts/100 heart beats; P = 0.01) but because heart rate rose less (+15 ± 3 vs. +19 ± 2 bpm; P = 0.03), exercise induced similar reductions in burst frequency (P = 0.25). Contrary to our initial hypothesis, with advancing age, mild- to moderate-intensity dynamic leg exercise elicits a greater rise in systolic blood pressure and a larger fall in MSNA.
Notarius et al. (Tue,) conducted a observational in Healthy subjects (n=36). 1-leg cycling in middle-aged subjects vs. 1-leg cycling in young subjects was evaluated on Change in MSNA burst incidence during moderate 1-leg cycling (bursts/100 heart beats) (p=0.01). Mild- to moderate-intensity dynamic leg exercise in middle-aged subjects elicited a larger fall in MSNA burst incidence compared to young subjects (-19 vs -11 bursts/100 heart beats; P=0.01).