Summary: Passive exercise increases cerebral blood flow and improves executive function, providing the same cognitive benefits as more active exercise.
Font: University of Western Ontario
A new study by Western kinesiology graduate students found that passive exercise leads to increased cerebral blood flow and improves executive function, providing the same cognitive benefits as active exercise.
Published in psychophysiologyThe study is the first to look at whether there would be brain health benefits during passive exercise in which a person’s limbs are moved through an external force—in this case, bicycle pedals pushed by a mechanically powered flywheel.
During a 20-minute session with healthy young adults, the team assessed executive function at the start of the study, before the participants exercised, and compared post-exercise data. They found an improvement in executive function of the same magnitude for the passive and active exercise conditions, without an increase in heart rate or diastolic blood pressure.
Executive function is a higher-order cognitive ability that enables people to make plans and supports activities of daily living. People who have mild cognitive impairments, such as people who experience symptoms of early-stage Alzheimer’s disease, may find that their executive function is negatively affected.
Previous research has documented that active exercise, in which a person activates their muscles of their own free will, can increase blood flow to the brain and improve executive function. Passive exercise also increases blood flow to the brain, but this is significantly less well documented.
“In terms of passive exercise, we were only able to hypothesize about the outcome because this type of research hadn’t been done before,” said Matthew Heath, professor of kinesiology and supervisor of the study.
During passive exercise, a person’s limbs move and their muscle receptors stretch. That information is sent to the brain, signaling that more blood is needed in the moving areas of the body and in the connected regions of the brain. This increase in cerebral blood flow, although significantly less than with active exercise, produced improvements in executive function of a similar magnitude, an exciting result for the researchers.
“The potential impact for people with limited or no mobility could be profound. If done regularly, the increased blood flow to the brain and the resulting improvement in executive function will hopefully become a combined effect that will have a significant impact on cognitive health and executive function,” explained Heath.
Further study could be improved by looking at whether the benefit for executive function persists at longer time intervals after exercise, as well as by including more diverse participants (for example, those who are older or have health problems).
Heath and his team see great potential in the use of passive exercises in nursing homes or rehabilitation programs for people recovering from musculoskeletal injuries who are unable to exercise with weights.
The study was led by master’s student Mustafa Shirzad and co-authored by graduate students Benjamin Tar, Connor Dalton, James Van Riesen, and Michael Marsala. Heath was the corresponding author.
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Author: kim mcready
Font: University of Western Ontario
Contact: Kim McCready – University of Western Ontario
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original research: Closed access.
“Passive exercise increases cerebral blood flow velocity and supports a post-exercise executive function benefit” by Mustafa Shirzad et al. psychophysiology
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Passive exercise increases cerebral blood flow velocity and supports a post-exercise executive function benefit
Executive function involves high-level cognitive control that supports activities of daily living. The literature has shown that a single bout of exercise involving voluntary muscle activation (ie, active exercise) improves executive function and that an increase in cerebral blood flow (CBF) may contribute to this benefit.
However, it is unknown whether nonvoluntary exercise (ie, passive exercise) in which an individual’s limbs are moved through an external force elicits a similar executive function benefit. This is an important question given that the proprioceptive and feedback drive of passive exercise increases CBF independently of the metabolic demands of active exercise.
Here, in a procedural validation of the participants (north = 2) used a cycle ergometer to complete separate active and passive (via a mechanically actuated flywheel) 20-minute exercise conditions and a no-exercise control condition. Electromyography showed that passive exercise did not increase agonist muscle activation or increase ventilation or gas exchange variables (i.e., VO max.two and V̇COtwo).
In a main experiment the participants (north = 28) completed the same exercise and control conditions and transcranial Doppler ultrasound showed that active and passive exercise (but not the control condition) increased CBF via the middle cerebral artery (ps<.001); although the magnitude was lower during passive exercise.
In particular, the antisaccade reaction times before and immediately after each condition showed that the active (p < .001) and passive (p = .034) exercise improved an oculomotor-based measure of executive function, whereas no benefit was seen in the control condition (p= .85).
Consequently, the results show that passive exercise ‘increases’ an oculomotor-based measure of executive function and support converging evidence that increasing CBF mediates this benefit.
