A Randomized Controlled Trial of High-Intensity Exercise and Executive Functioning in Cognitively Normal Older Adults

•This novel randomized controlled trial assessed the effect of a systematically manipulated exercise intervention (high-intensity versus moderate-intensity versus inactive control) on five Executive Function subdomains (Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Non-verbal Reasoning) in a group of cognitively normal older adults.•The primary analysis did not show mean differences in Executive Function scores between the high-intensity, moderate intensity, or inactive control groups. However, on the basis of individual change scores, cardiorespiratory fitness was found to associate positively with the Executive Function subdomains of Updating/Working Memory and Verbal Generativity for intervention, but not control participants.•While, at the aggregate level, we did not find evidence that six months of high-intensity aerobic exercise improves executive function in older adults, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in the Executive Function subdomains of Updating/ Working Memory and Verbal Generativity. There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function. Ninety-nine cognitively normal participants (age = 69.10 ± 5.2 years; n = 54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO2peak. First, the exercise intervention was found to increase cardiorespiratory fitness (VO2peak) in the intervention groups, in comparison to the control group (F =10.40, p≤0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis