Increased cerebral blood flow supports a single-bout postexercise benefit to executive function: evidence from hypercapnia

Abstract

A single bout of aerobic exercise improves executive function; however, the mechanism for the improvement remains unclear. One proposal asserts that an exercise-mediated increase in cerebral blood flow (CBF) enhances the efficiency of executive-related cortical structures. Here, participants completed separate 10-min sessions of moderate to heavy intensity aerobic exercise, a hypercapnic environment (i.e., 5% CO2), and a non-exercise and non-hypercapnic control condition. The hypercapnic condition was included because it produces an increase in CBF independent of metabolic demands. An estimate of CBF was achieved via transcranial doppler ultrasound and near-infrared spectroscopy that provided measures of middle cerebral artery blood velocity (BV) and deoxygenation (HHb), respectively. Exercise intensity was adjusted to match participant-specific change in BV and HHb associated with the hypercapnic condition. Executive function was assessed prior to and after each session via antisaccades (i.e., saccade mirror-symmetrical to a target) because the task is mediated via the same executive networks that demonstrate task-dependent modulation following single- and chronic-bouts of aerobic exercise. Results showed that hypercapnic and exercise conditions were associated with comparable BV and HHb changes, whereas the control condition did not produce a change in either metric. In terms of antisaccade performance, the exercise and hypercapnic - but not control - conditions demonstrated improved post-condition reaction times (RT), and the magnitude of the hypercapnic and exercise-based increase in estimated CBF was reliably related to the post-condition improvement in RT. Accordingly, results evince that an increase in CBF represents a reliable candidate for a post-exercise improvement in executive function.

Evaluating the efficacy of an iPad® app in determining a single bout of exercise benefit to executive function

“…Instead, our findings add to convergent literature asserting that a single bout of exercise improves executive function (Chang et al, 2012 ; Lambourne & Tomporowski, 2010 ; Ludyga et al, 2016 ). As indicated in the Introduction, the improvement may reflect an exercise-mediated increase in cerebral blood flow (Lucas et al, 2012 ; Tari et al, 2020 ), biomolecule concentration (Knaepen et al, 2010 ; Zouhal et al, 2008 ) and/or resting state functional connectivity that enhances the efficiency and effectiveness of the local neural circuitry supporting executive function (i.e., the hemo-neural hypothesis; see Moore & Cao, 2008 ). Regardless of the mechanism, or mechanisms, the magnitude of the pre- to postexercise decrease in antipointing RT and reported effect size (d z = 0.90) is markedly similar to five previous studies employing a lab-based assessment of antisaccade performance (i.e., average postexercise RT reduction of 21 ms with a pooled effect size of 1.01) (Dirk et al, 2020 ; Heath et al, 2018 ; Petrella et al, 2019 ; Samani & Heath, 2018 ; Tari et al, 2020 ).…”

“…Post-assessment pro- and antipointing trials were completed ~ 4-min after the end of the exercise and control sessions. The basis for the 4-min delay was to allow HR in the exercise session to fall below 100 bpm and is the same protocol used in previous lab-based and continuous HR monitoring studies by our group (Dirk et al, 2020 ; Heath et al, 2018 ; Petrella et al, 2019 ; Shukla & Heath, 2021 ; Tari et al, 2020 ). Each pro- and antipointing assessment required approximately 12-min to complete.…”

“…As a result, tasks involving conjoint executive and non-executive components may – at times – be insufficient for detecting postexercise executive function benefits. In support of this view, recent studies employing the antisaccade task demonstrated that a single bout of exercise elicits a robust executive function benefit (Dirk et al, 2020 ; Heath et al, 2018 ; Petrella et al, 2019 ; Samani & Heath, 2018 ; Tari et al, 2020 ). Antisaccades require a goal-directed eye movement mirror-symmetrical to a target and the non-standard nature of the task (i.e., decoupling the spatial relations between stimulus and response) results in longer reaction times (RT) and less accurate and more variable endpoints than their prosaccade (i.e., saccade toward a target) counterparts (for review see, Munoz & Everling, 2004 ).…”

“…Indeed, Chang et al concluded that the largest positive benefit to cognition occurs 11 to 20 min (see also Lambourne & Tomporowski, 2010 ) following cessation of a 20-min bout of moderate-intensity exercise. It is, however, important to recognize that work has shown that young and older adults exhibit a benefit up to 60-min postexercise (Hung et al, 2013 ; Joyce et al, 2009 ; Shukla & Heath, 2021 ) for an exercise duration as brief as 10-min (Johnson et al, 2016 ; Samani & Heath, 2018 ; Tari et al, 2020 ) and across the continuum of metabolically sustainable work rates (i.e., from light to very heavy-intensity) (Heath et al, 2018 ; Petrella et al, 2019 ; Tari et al 2021 ). A fourth, and perhaps most salient moderator, is the cognitive domain that is assessed.…”

ABBaH teens: Activity Breaks for Brain Health in adolescents: study protocol for a randomized crossover trial

“…One important mechanism that may explain the effects of physical activity on cognitive performance is changes in blood circulation in the cerebral cortex, especially in the frontal lobe (prefrontal), which is involved in solving cognitively demanding tasks [ 16 , 17 ], but the majority of research has been in adults. Generally, results have revealed that a single bout of exercise can elicit immediate cognitive task-related increases on cerebral blood flow post exercise cessation [ 18 – 22 ], but also decreases or no effects have been observed [ 23 , 24 ]. Reasons for differing results are partly related to the moderating effects of timing, duration, and intensity of the physical activity, and the timing and type of cognitive test performed.…”