Cerebral blood flow and executive function changes in response to active and passive aerobic exercise

A single bout of 'active' aerobic exercise increases cerebral blood flow (CBF), and this change has been linked to improved executive function (EF). Interestingly, passive exercise, wherein an individual’s limbs are moved via an external force, similarly increases CBF and provides a postexercise EF benefit. The CBF change during passive exercise is attributed to mechanoreceptive feedback to the primary somatosensory cortex that increases cardiac output and stroke volume. This research examined whether the frequency of afferent stimulation during passive exercise impacts the magnitude of a CBF response and a putative postexercise EF benefit. Sixteen participants underwent five 20-minute sessions of "low" (55 rpm) and "high" (85 rpm) frequency active and passive cycling sessions, plus a non-exercise control session. Pre- and postexercise middle cerebral artery velocity (MCAv) changes were measured using Transcranial Doppler ultrasound (TCD) to estimate CBF, and changes in EF were assessed via the antisaccade task. The magnitude of baseline to steady-state changes in MCAv increased from the “low” to “high” frequency passive exercise sessions and exhibited a further step-wise increment for the “low” and “high” frequency active exercise sessions (ps<.001). In turn, antisaccade reaction times showed a pre- to postexercise reduction across “low” and “high” frequency passive and active exercise sessions (ps<0.03), and equivalence tests showed that the magnitude of this change did not vary between sessions (ps<0.05). A single bout of passive or active exercise benefits EF and such a benefit is not linked to the magnitude of an exercise-mediated increase in CBF.