The relationship between aerobic fitness and low-flow-mediated constriction in older adults
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Aerobic fitness is directly related to favorable vasodilatory (i.e., flow-mediated dilation; FMD) and vasoconstrictor functions (i.e., low-flow-mediated constriction; L-FMC) in young adults. Furthermore, aerobically fit older adults (OA) have larger FMD responses than their less fit peers. However, the relationship between aerobic fitness and vasoconstrictor responsiveness is unknown in OA. We hypothesized that OA who are more aerobically fit will exhibit a greater L-FMC response than their less fit counterparts.
Forty-seven healthy OA (67 ± 5 years) were divided into less (LF; n = 27) and more aerobically fit (MF; n = 20) groups based on peak oxygen consumption (VO2peak). VO2peak was determined from an incremental maximal cycle ergometer test via indirect calorimetry. FMD and L-FMC were assessed in the brachial artery via high-resolution duplex ultrasonography.
VO2peak (18.3 ± 3.2 versus 29.1 ± 5.8 ml/kg/min; P < 0.001) and L-FMC were both greatest in the MF versus LF groups (–1.2 ± 0.9 vs. − 0.5 ± 0.6%; P = 0.01). Furthermore, the MF group had an enhanced FMD response (5.6 ± 1.5 versus 3.9 ± 1.2%; P < 0.001). In the pooled sample, there was a negative correlation (r = − 0.52; P < 0.001) between VO2peak (22.9 ± 7.0 ml/kg/min) and L-FMC (–0.8 ± 0.8%).
In an older population, greater aerobic fitness was associated with a more favorable vasoconstrictor response to low-flow conditions. Interventional or longitudinal aerobic exercise training studies are warranted in this population to determine the impact of training-induced increases in VO2peak on L-FMC.
KeywordsEndothelial function Vascular aging Arterial reactivity Cardiorespiratory fitness
Body mass index
Canadian Society for Exercise Physiology
Coefficient of variation
Diastolic blood pressure
More aerobically fit
Less aerobically fit
Mean arterial pressure
Systolic blood pressure
Shear rate area under the curve
Volume of oxygen consumption
Peak volume of oxygen consumption
Support provided by: Canadian Foundation for Innovation: Leader’s Opportunity Fund (DSK), Faculty of Health Professions Research Development (DSK), NSHRF Development/Innovation (DSK and SM) grants, as well as, the Acadia University McCain Foundation Fund (SM). MWO was supported by a Heart and Stroke BrightRed Scholarship, NS Graduate Scholarship and an NSHRF Scotia Scholars Award.
The study was designed by MWO, SM and DSK; data were collected by SAR, JAJ and MWO; data were analyzed by SAR, JAJ and MWO; data interpretation and manuscript preparation were undertaken by MWO and DSK. All authors approved the final version of the paper.
Compliance with ethical standards
Conflict of interest
The authors have no conflicts of interest to report.
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