title: Cardiorespiratory fitness modulates the acute flow-mediated dilation response following high-intensity but not moderate-intensity exercise in elderly men.
abstract: Impaired endothelial function is observed with aging and in those with low cardiorespiratory fitness (V̇o2peak). Improvements in endothelial function with exercise training are somewhat dependent on the intensity of exercise. While the acute stimulus for this improvement is not completely understood, it may, in part, be due to the flow-mediated dilation (FMD) response to acute exercise. We examined the hypothesis that exercise intensity alters the brachial (systemic) FMD response in elderly men and is modulated by V̇o2peakForty-seven elderly men were stratified into lower (V̇o2peak= 24.3 ± 2.9 ml·kg-1·min-1;n= 27) and higher fit groups (V̇o2peak= 35.4 ± 5.5 ml·kg-1·min-1;n= 20) after a test of cycling peak power output (PPO). In randomized order, participants undertook moderate-intensity continuous exercise (MICE; 40% PPO) or high-intensity interval cycling exercise (HIIE; 70% PPO) or no-exercise control. Brachial FMD was assessed at rest and 10 and 60 min after exercise. FMD increased after MICE in both groups {increase of 0.86% [95% confidence interval (CI), 0.17-1.56],P= 0.01} and normalized after 60 min. In the lower fit group, FMD was reduced after HIIE [reduction of 0.85% (95% CI, 0.12-1.58),P= 0.02] and remained decreased at 60 min. In the higher fit group, FMD was unchanged immediately after HIIE and increased after 60 min [increase of 1.52% (95% CI, 0.41-2.62),P< 0.01, which was correlated with V̇o2peak,r= 0.41;P< 0.01]. In the no-exercise control, FMD was reduced in both groups after 60 min (P= 0.05). Exercise intensity alters the acute FMD response in elderly men and V̇o2peakmodulates the FMD response following HIIE but not MICE. The sustained decrease in FMD in the lower fit group following HIIE may represent a signal for vascular adaptation or endothelial fatigue.NEW & NOTEWORTHYThis study is the first to show that moderate-intensity continuous cycling exercise increased flow-mediated dilation (FMD) transiently before normalization of FMD after 1 h, irrespective of cardiorespiratory fitness level in elderly men. Interestingly, we show increased FMD after high-intensity cycling exercise in higher fit men, with a sustained reduction in FMD in lower fit men. The prolonged reduction in FMD after high-intensity cycling exercise may be associated with future vascular adaptation but may also reflect a period of increased cardiovascular risk in lower fit elderly men.
authors.affiliation: VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Queensland, Australia; tbailey@usc.edu.au.
authors.forename: Tom G
authors.identifier: http://orcid.org/0000-0001-8531-2780
authors.initials: TG
authors.lastname: Bailey
authors.affiliation: VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Queensland, Australia.
authors.forename: Maria
authors.initials: M
authors.lastname: Perissiou
authors.affiliation: VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Queensland, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Windsor
authors.affiliation: VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Queensland, Australia.
authors.forename: Fraser
authors.initials: F
authors.lastname: Russell
authors.affiliation: Queensland Research Centre for Peripheral Vascular Disease, James Cook University and the Townsville Hospital, Townsville, Australia.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Golledge
authors.affiliation: School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Australia; and.|Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Green
authors.affiliation: VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Queensland, Australia.
authors.forename: Christopher D
authors.identifier: http://orcid.org/0000-0001-8076-8789
authors.initials: CD
authors.lastname: Askew
mesh_terms: D000368:Aged; D001916:Brachial Artery / Q000502:physiology; D000072599:Cardiorespiratory Fitness / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology*; D012307:Risk Factors; D014664:Vasodilation / Q000502:physiology*
keywords: FMD; aging; cardiorespiratory fitness; endothelial function; exercise