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Heterogeneous vascular responses to hypoxic forearm exercise in young and older adults.

Authors
  • Limberg, Jacqueline K1
  • Evans, Trent D
  • Pegelow, David F
  • Eldridge, Marlowe W
  • Sebranek, Joshua J
  • Proctor, Lester T
  • Schrage, William G
  • 1 Department of Kinesiology, School of Education, University of Wisconsin, 2000 Observatory Avenue, Rm 1149A, Madison, WI 53703, USA.
Type
Published Article
Journal
European Journal of Applied Physiology and Occupational Physiology
Publisher
Springer-Verlag
Publication Date
Aug 01, 2012
Volume
112
Issue
8
Pages
3087–3095
Identifiers
DOI: 10.1007/s00421-011-2280-x
PMID: 22198326
Source
Medline
License
Unknown

Abstract

We aimed to assess age-related differences in compensatory hypoxic vasodilation during moderate-to-high dynamic exercise at absolute workloads. We hypothesized healthy older adults (n = 12, 61 ± 1 years) would exhibit impaired hypoxic vasodilation at a moderate absolute workload, and this effect would be exaggerated at a higher workload when compared to young adults (n = 17, 27 ± 2 years). Forearm blood flow (FBF) was measured with Doppler ultrasound. Dynamic forearm exercise (20 contractions/min) was completed at two absolute workloads (8 and 12 kg) under normoxic (0.21 FiO2, ~98% SpO2) and isocapnic hypoxic (~0.10 FiO2, 80% SpO2) conditions performed in random order. FBF was normalized as forearm vascular conductance (FBF / mean arterial blood pressure = FVC) to control for differences in blood pressure and to assess vasodilation. FVC increased with exercise and hypoxia (main effects, p < 0.05); vascular responses were not different between young and older adults (interaction effect exercise × group p = 0.37 and hypoxia × group p = 0.96). Results were confirmed when analyzed as either an absolute or relative change in FVC (ΔFVC and %ΔFVC, respectively). Although group responses to hypoxia were not different, individual results were highly variable (i.e., some adults constricted and others dilated to hypoxia). These data suggest (1) compensatory hypoxic vasodilation in older adults is not impaired during forearm exercise at both moderate and higher absolute exercise intensities, and (2) vascular responses to hypoxia are heterogeneous in both young and older adults. Results suggest unique individual differences exist in factors regulating vascular responses to hypoxia.

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