Study: HIIT Can Increase Cerebral Blood Flow

High-intensity interval training (HIIT) increases cerebral blood flow, improves cerebrovascular health, and may offset cognitive decline, according to a new study (Klein et al., 2019) from researchers at the University of Queensland in Australia.

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Aging brains tend to have less cerebral blood flow and are at an increased risk of cerebrovascular disease. Notably, the researchers found that HIIT may be more effective than continuous aerobic exercise in terms of increasing blood flow to the brain in older adults. These findings were recently published in the journal Medicine & Science in Sports & Exercise.

"As we age, the flow of blood to the brain and arterial function decreases. These factors have been linked to a risk of cognitive decline and cardiovascular events, such as stroke," co-author Tom Bailey from UQ's School of Human Movement and Nutrition Sciences said in a statement. "Finding ways to increase brain blood flow and function in older adults is vital. This study aimed to identify the type or format of exercise that causes the greatest increases in brain blood flow, so we could help to optimize exercise programs to enhance brain function."

For this study, Bailey and an international team of researchers focused on changes in cerebral blood flow during 10 minutes of interval training versus work-matched periods of continuous cardiovascular exercise on a stationary bicycle. High-intensity interval training is characterized by short bouts of vigorous physical activity that are separated by periods of rest; this exertion-followed-by-recovery cycle is repeated several times during each HIIT workout.

"One of the key takeaways from the study was that both the exercise and the rest period were important for increasing brain blood flow in older adults," Bailey said. "This study shows that interval-based exercise was as effective as continuous exercise for increasing brain blood flow in older adults during the periods of activity, and more effective than continuous exercise when we measured the overall blood flow increases during both the exercise and the rest periods."

This study has some limitations: The cohort was small, and the researchers only focused on short-term increases of cerebral blood flow during interval and continuous exercise in older and younger men. The next step for Bailey and colleagues is to investigate the potential long-term benefits of HIIT and increased cerebral blood flow on brain health in men and women of all ages in a more extensive study.

The latest findings on the brain benefits of HIIT for older adults dovetail with another recent study, "Association of Lifestyle and Genetic Risk with Incidence of Dementia," which found that regular exercise is one of four lifestyle choices that may offset the risk of cognitive decline.

If you need some motivation to kickstart an exercise routine that includes intervals, listening to a personalized playlist of songs that inspire you is an evidence-based way to make HIIT more enjoyable. A recent study, "Let's Go: Psychological, Psychophysical, and Physiological Effects of Music During Sprint Interval Exercise," led by Matthew Stork of UBC Okanagan found that "The application of music during [intervals] has the potential to enhance feelings of pleasure, improve enjoyment, and elevate the performance of [HIIT]." For more see, "Reluctant to Try HIIT? Music Could Be a Game-Changer."

DISCLAIMER: Please use common sense and consult with your primary care physician before engaging in any new type of physical activity such as HIIT—especially if you haven't participated in any high-intensity physical activity recently.