Active Voice: Two Worlds Collide — Bridging Acute and Chronic Exercise Paradigms to Understand How Physical Activity Improves Cognition
By Michelle W. Voss, Ph.D.

Michelle W. Voss
It is generally accepted that what is good for the heart is good for the brain, and physical activity is no exception. The 2018 Physical Activity Guidelines for Americans summarized evidence of a connection between physical activity and brain and cognitive outcomes. A review of those guidelines published in Medicine & Science in Sports & Exercise® (MSSE) concluded there is evidence that regular moderate- to vigorous-intensity physical activity benefits the brain. Also, a recent consensus statement by the National Academies concluded that evidence for exercise to reduce age-related cognitive decline is promising. However, both reviews emphasize caution in thinking of exercise as a one-size-fits-all cure-all. We need a better understanding of why some people reap more brain benefits from exercise than others and what factors can be modified to more effectively prescribe exercise for cognitive health.

The immediate transient response to exercise in the brain may hold clues to heterogeneity of training benefits on cognition. Recent studies reported moderate- to vigorous-intensity physical activity acutely improves cognition during the post-recovery period. These acute effects could be a snapshot of physiological adaptations that accrue with continued training. We hypothesized that those with a stronger acute response in the brain and cognitive performance would have a stronger training response in the same outcomes.

To test this idea, we studied 34 cognitively normal older adults and reported the results in the January 2020 issue of MSSE. The two major findings were: 1) acute benefits were positively related to training outcomes, and 2) the amount of transient cognitive benefit from 20 minutes of moderate-intensity exercise was comparable to the benefit from three months of training in the same participants. This suggests that neurobiological mechanisms involved in training-related change in cognition and the brain were also activated acutely. This is important because the acute effects must have been functional in nature but enabled the same performance boost as months of training. If this can be replicated and extended with specification of key pathways between exercising muscle and brain, then within-subject studies that block or augment their activation become feasible and ethical. This would move us closer to a goal of personalized physical activity recommendations for cognitive benefits.

Our initial findings set the stage for tackling important follow-up questions, such as: How did exercise make this functional plasticity possible? Were the brain networks affected functionally the same as those that adapted structurally from exercise training? Would these acute exercise effects predict only exercise training outcomes, or could they be a biomarker of the capacity for experience-dependent plasticity more generally?

What does this mean for the broader field? This is the first evidence supporting the idea that acute exercise effects on cognition and the brain are a transient snapshot of effects that accumulate with continued training. This initial study was designed to test the proof-of-concept rather than to be definitive. Therefore, replication from larger samples and extensions to more cognitive and brain outcomes will be critical to put these novel findings to the test.

About the author:
Michelle W. Voss, Ph.D., is an assistant professor in the Department of Psychological and Brain Sciences at the University of Iowa in Iowa City, Iowa, where she directs the Health, Brain and Cognition Lab. Her research investigates how cognition and the brain change with aging and how negative effects of brain aging that impair cognition and everyday function may be non-pharmacologically stabilized or reversed with modifiable factors like physical activity. Learn more about Dr. Voss’ lab or connect with her by email.

Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent positions or policies of ACSM. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB.