Pedal cadence differentially impacts cerebral blood flow but not a postexercise executive function benefit: Evidence from active and passive exercise

An exercise-induced increase in cerebral blood flow (CBF) serves as a candidate mechanism underlying a postexercise executive function (EF) benefit. Here, healthy young adults completed four 20-min interventions of active and passive (via mechanical flywheel) cycle ergometry at pedal cadences of 55 and 85 revolutions per minute (rpm). Active and passive exercise were used because each modality increases CBF - albeit via distinct mechanisms - and different pedal cadences were used because an increase in passive exercise cadence is thought to increase CBF. Hence, we sought to determine whether the magnitude of a passive exercise increase in CBF influences the magnitude of a postexercise EF benefit. Transcranial Doppler ultrasound measured middle cerebral artery velocity (MCAv) to estimate CBF and the antisaccade task completed at pre- and post-intervention was used to assess changes in EF. Results showed that active exercise produced a larger baseline to steady state increase in MCAv than passive exercise, and both modalities showed an increase in MCAv with increasing pedal cadence. Moreover, both modalities produced a post-intervention reduction in antisaccade reaction times (RTs); however, frequentist and Bayesian statistics indicated the RT benefit did not vary with exercise modality nor pedal cadence, and the RT reduction was not correlated with active or passive exercise-mediated changes in CBF changes. Accordingly, active and passive exercise provide a comparable immediate postexercise EF benefit, and an exercise-mediated change in CBF does not provide a unitary account for the benefit.