The Effects of Short‐Term High‐Intensity Interval Versus Moderate‐Intensity Continuous Training on Vascular Function in Older Adults
Authors: O'Brien Myles William , Robinson Susan , Mekary Said , Kimmerly Derek 
Published: June 2021

In younger adults, high‐intensity interval training (HIIT) improves aerobic fitness and upper limb vascular health more than moderate‐intensity continuous training (MICT). However, it is unclear whether these superior HIIT‐mediated improvements can be translated to an older adult population. Additionally, there is a paucity of research comparing HIIT versus MICT within lower‐limb vascular beds, which are more susceptible to the development of atherosclerosis. We tested the hypothesis that six‐weeks of HIIT would improve brachial (BA) and popliteal artery (PA) endothelial function more than MICT in older adults. Aerobic fitness (VO2peak) and vascular function were assessed before and after exercise training in 15 older adults (HIIT: n=6, 2♂, 66±6 years, BMI=26±3 kg/m2; MICT: n=9, 3♂, 69±7 years, BMI=26±3 kg/m2). The supervised exercise programs were conducted 3 days/week. HIIT consisted of two, 20 minute bouts separated by 5‐minutes of passive recovery, each bout was comprised of repeated 15‐second intervals alternating between 100% maximal power output and passive recovery. MICT bouts were isocaloric to HIIT and consisted of continuous exercise at 60% of maximal power for 34 minutes. Vascular function was examined using the flow‐mediated dilation (FMD) technique in the BA and PA via high‐resolution duplex ultrasonography. Nitroglycerin‐mediated dilation (NMD, 4 mg sublingual spray) was also assessed in the PA as a measure of endothelial‐independent dilation. VO2peak improved 21% following HIIT (22±7 to 28±7 mlO2/kg/min) and 25% after MICT (23±4 to 28±7 mlO2/kg/min). Similar increases (both, p<0.05) in BA‐FMD and PA‐FMD were observed following HIIT and MICT. Specifically, BA‐FMD increased from 4.3±1.7% to 6.9±1.6% and 4.7±1.9% to 7.1±1.7% after HIIT and MICT, respectively. PA‐FMD improved from 2.3±1.3% to 4.1±1.4% after HIIT and from 2.0±0.9% to 3.5±1.5% after MICT. No changes in resting BA and PA diameters, nor PA‐NMD were observed in either group (all p>0.05). These data suggest that 6‐weeks of HIIT and MICT produce similar improvements in aerobic fitness, upper‐ and lower‐limb vascular endothelial function in older adults. The relatively short training period may have limited our ability to detect differences in these outcomes between HIIT and MICT, as well as, to observe aerobic training‐induced arterial structural adaptations in older adults. These findings enforce the beneficial effects of aerobic exercise training as a primary component of healthy aging.Support or Funding InformationSupport provided by: Canadian Foundation for Innovation: Leaders Opportunity Fund, Faculty of Health Professions Research Development, and NSHRF Development/Innovation grants. MWO was a recipient of a NS Graduate Scholarship, NSHRF Scotia Scholar Award and Heart & Stroke BrightRed Award.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.