Effect of healthy aging and sex on middle cerebral artery blood velocity dynamics during moderate-intensity exercise

Blood velocity measured in the middle cerebral artery (MCA ) increases with finite kinetics during moderate-intensity exercise, and the amplitude and dynamics of the response provide invaluable insights into the controlling mechanisms. The MCA response after exercise onset is well fit to an exponent...

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Bibliographic Details
Published in:American journal of physiology. Heart and circulatory physiology 2018-09, Vol.315 (3), p.H492-H501
Main Authors: Ward, Jaimie L, Craig, Jesse C, Liu, Yumei, Vidoni, Eric D, Maletsky, Rebecca, Poole, David C, Billinger, Sandra A
Format: Article
Language:English
Subjects:
Adult
Adults
Aged
Aged, 80 and over
Aging
Aging - physiology
Amplitudes
Blood pressure
Carbon dioxide
Cerebrovascular Circulation
Cerebrovascular system
Exercise
Female
Fitness
Geriatrics
Hemodynamics
Humans
Kinetics
Male
Middle Cerebral Artery - growth & development
Middle Cerebral Artery - physiology
Muscles
Older people
Physical fitness
Sex Factors
Skeletal muscle
Therapeutic applications
Time constant
Veins & arteries
Velocity
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Summary:Blood velocity measured in the middle cerebral artery (MCA ) increases with finite kinetics during moderate-intensity exercise, and the amplitude and dynamics of the response provide invaluable insights into the controlling mechanisms. The MCA response after exercise onset is well fit to an exponential model in young individuals but remains to be characterized in their older counterparts. The responsiveness of vasomotor control degrades with advancing age, especially in skeletal muscle. We tested the hypothesis that older subjects would evince a slower and reduced MCA response to exercise. Twenty-nine healthy young (25 ± 1 yr old) and older (69 ± 1 yr old) adults each performed a rapid transition from rest to moderate-intensity exercise on a recumbent stepper. Resting MCA was lower in older than young subjects (47 ± 2 vs. 64 ± 3 cm/s, P < 0.001), and amplitude from rest to steady-state exercise was lower in older than young subjects (12 ± 2 vs. 18 ± 3 cm/s, P = 0.04), even after subjects were matched for work rate. As hypothesized, the time constant was significantly longer (slower) in the older than young subjects (51 ± 10 vs. 31 ± 4 s, P = 0.03), driven primarily by older women. Neither age-related differences in fitness, end-tidal CO , nor blood pressure could account for this effect. Thus, MCA kinetic analyses revealed a marked impairment in the cerebrovascular response to exercise in older individuals. Kinetic analysis offers a novel approach to evaluate the efficacy of therapeutic interventions for improving cerebrovascular function in elderly and patient populations. NEW & NOTEWORTHY Understanding the dynamic cerebrovascular response to exercise has provided insights into sex-related cerebrovascular control mechanisms throughout the aging process. We report novel differences in the kinetics response of cerebrovascular blood velocity after the onset of moderate-intensity exercise. The exponential increase in brain blood flow from rest to exercise revealed that 1) the kinetics profile of the older group was blunted compared with their young counterparts and 2) the older women demonstrated a slowed response.
ISSN:0363-6135
1522-1539
DOI:10.1152/ajpheart.00129.2018