Study Separates Exercise-Related Brain Changes From Practice Effects

A new functional MRI study suggests that a single session of aerobic exercise can alter regional brain activity while people perform cognitive tasks—but the researchers also found that repeating the same tasks may substantially change brain activity on its own.

Researchers from Japan’s National Institute of Advanced Industrial Science and Technology, working with the University of Texas Southwestern Medical Center, studied healthy young and older adults before and after acute aerobic exercise. Their findings were published in the Journal of Magnetic Resonance Imaging.

The study used a crossover fMRI design with repeated measurements of brain activity. This allowed the researchers to examine two effects that are often difficult to disentangle: changes associated with exercise and changes caused by performing a cognitive task repeatedly between exercise intervals.

The researchers reported that aerobic exercise altered patterns of activity in specific brain regions during cognitive tasks, suggesting that exercise may influence the neural processes involved in executive function. The study did not establish that exercise prevents dementia or cognitive decline, nor did it demonstrate a long-term clinical benefit.

Task repetition produced a separate and pronounced effect. In older adults, lower brain activity associated with repeating the task was positively correlated with task performance. According to the researchers, this relationship may indicate that reduced activity as participants become familiar with a task reflects more efficient processing rather than poorer function.

That distinction is important for studies of exercise and cognition. Earlier research has reported acute improvements in cognitive-task performance after aerobic exercise, but behavioral scores alone do not show how brain activity changes during the task. If repeated testing is not accounted for, practice or habituation effects could be mistaken for effects of exercise.

The research team used an advanced neuroimaging facility at AIST that supports repeated functional MRI measurements. The approach was designed to make exercise-related changes in brain activity easier to distinguish from changes caused by task repetition.

The findings add a brain-imaging component to research on exercise and cognitive function, while also underscoring that the act of repeatedly performing a task can influence neural efficiency. The researchers said the method could support future work on interventions intended to maintain cognitive function in older adults. In the current study, however, the evidence concerns short-term changes in brain activity and task-related patterns, not proof that exercise extends cognitive health or prevents dementia.