Active and passive exercise provide a comparable immediate postexercise executive function benefit, and an exercise-mediated change in cerebral blood flow does not provide a unitary account for the benefit.
Key Findings
Results
Active exercise produced a larger baseline to steady-state increase in middle cerebral artery velocity (MCAv) than passive exercise.
MCAv was measured via transcranial Doppler ultrasound to estimate cerebral blood flow (CBF)
Four 20-minute interventions were completed: active and passive cycle ergometry at pedal cadences of 55 and 85 rpm
Passive exercise was conducted via a mechanical flywheel, which increases CBF via distinct mechanisms compared to active exercise
The modality difference in MCAv increase was consistent across both pedal cadences tested
Results
Both active and passive exercise modalities showed an increase in MCAv with increasing pedal cadence (from 55 to 85 rpm).
Cadence was manipulated at 55 and 85 revolutions per minute (rpm) for both modalities
An increase in passive exercise cadence is theorized to increase CBF, which was confirmed in this study
Active exercise also showed the cadence-dependent MCAv increase
The cadence effect on MCAv was observed across both active and passive exercise conditions
Results
Both active and passive exercise modalities produced a postintervention reduction in antisaccade reaction times, indicating an executive function benefit.
The antisaccade task was used to assess executive function at pre- and postintervention timepoints
Antisaccade reaction times (RTs) were reduced following both active and passive exercise
The RT reduction occurred regardless of exercise modality
The antisaccade task is an established measure of executive function requiring inhibitory control
Results
The postexercise executive function benefit (RT reduction) did not vary with exercise modality or pedal cadence.
Both frequentist and Bayesian statistical approaches indicated no significant difference in RT benefit between modalities
Neither active nor passive exercise at 55 rpm vs. 85 rpm produced differential RT improvements
Despite modality differences in MCAv magnitude, the EF benefit was comparable across conditions
Bayesian statistics were used to provide additional evidence for the null effect of modality and cadence on EF benefit
Results
The postexercise executive function RT reduction was not correlated with exercise-mediated changes in cerebral blood flow for either active or passive exercise.
Correlation analyses were performed between MCAv changes and antisaccade RT changes for both modalities
No significant correlation was found between CBF change magnitude and EF benefit magnitude in either active or passive conditions
This dissociation between CBF changes and EF benefits was observed despite passive exercise cadence successfully modulating MCAv
Results indicate that an exercise-based increase in CBF is 'not a primary moderator of a postexercise executive function benefit'
Methods
The study used passive exercise via mechanical flywheel and cadence manipulation as an experimental approach to isolate the role of CBF in postexercise executive function.
Healthy young adults completed four 20-minute interventions in a within-subjects design
Passive exercise was selected because it increases CBF via distinct mechanisms from active exercise (without requiring voluntary muscular effort)
Cadence conditions of 55 and 85 rpm were chosen because higher passive cadence was expected to produce greater CBF increases
This design allowed the researchers to manipulate CBF magnitude independently of other exercise-related physiological changes associated with active exercise
What This Means
This research suggests that exercising on a stationary bike — whether you pedal yourself (active exercise) or your legs are moved by a mechanical device (passive exercise) — produces similar improvements in executive function (the brain's ability to control attention and inhibit automatic responses) immediately after exercise. The study measured blood flow to the brain using an ultrasound technique and tested executive function using an eye-movement task that requires mental effort to suppress automatic responses. While active exercise increased brain blood flow more than passive exercise, and faster pedaling increased brain blood flow in both conditions, these differences in blood flow did not translate into differences in how much executive function improved after exercise.
Importantly, this research suggests that the amount of increased blood flow to the brain during exercise does not directly determine how much the brain benefits from exercise in terms of executive function. Even when the researchers deliberately manipulated brain blood flow by changing pedaling speed during passive exercise, this had no effect on the size of the post-exercise cognitive improvement. The brain blood flow changes and the executive function improvements were statistically unrelated to each other across all conditions tested.
These findings matter because cerebral blood flow has been widely proposed as a key mechanism explaining why exercise improves brain function. This study challenges that idea, suggesting that other factors — potentially including neurochemical changes, neural oscillations, or arousal-related processes — may be more important drivers of the immediate cognitive benefits of exercise. The finding that passive exercise (where no voluntary effort is required) also improves executive function is also notable, as it has implications for populations who cannot perform active exercise.
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Tari B, Rahimi A, Buwadi L, Qian Y, Zou L, Heath M. (2026). Pedal cadence differentially impacts cerebral blood flow but not a postexercise executive function benefit: evidence from active and passive exercise.. Journal of neurophysiology. https://doi.org/10.1152/jn.00572.2025