TY - JOUR
T1 - Heterogeneous vascular responses to hypoxic forearm exercise in young and older adults
AU - Limberg, Jacqueline K.
AU - Evans, Trent D.
AU - Pegelow, David F.
AU - Eldridge, Marlowe W.
AU - Sebranek, Joshua J.
AU - Proctor, Lester T.
AU - Schrage, William G.
N1 - Funding Information:
Acknowledgments We are grateful to the subjects for their participation. In addition, we extend many thanks to Jessica Danielson, John Harrell, Kathleen Grabowski, Adam Kiefer, Patrick Meyer, Caitlin Zillner, and Lee Linstroth for technical assistance. Thank you to Dr. Zhanhai Li, PhD and grant 1ULRR025011 from the Clinical and Translational Science Award (CTSA) program of the National Center for Research, National Institutes of Health for assistance with statistical analysis. This study was supported by grants from the American Federation on Aging Research #A08235 (WGS), American Heart Association pre-doctoral awards #0815622G (JKL) and #10PRE3870000 (JKL).
PY - 2012/8
Y1 - 2012/8
N2 - 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 FiO 2, ~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.
AB - 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 FiO 2, ~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.
KW - Aging
KW - Blood flow
KW - Functional hyperemia
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U2 - 10.1007/s00421-011-2280-x
DO - 10.1007/s00421-011-2280-x
M3 - Review article
C2 - 22198326
AN - SCOPUS:84864874129
SN - 1439-6319
VL - 112
SP - 3087
EP - 3095
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 8
ER -