About the Study

Researchers recruited 105 men and women aged 70 to 77 and split them into three groups. The first performed supervised exercise twice a week with high-intensity interval training (HIIT) at a 90% peak heart rate. The second did moderate-intensity training at 70% peak heart rate. The third, a control group, did at least 30 minutes of daily activity, but at a low intensity and didn’t have heart rate measured.1

Brain volume and cortical thickness—a measure of gray matter associated with cognition—as well as cardiorespiratory function were measured after one year, three years, and five years of exercise.1

Cardiorespiratory fitness increased significantly for all three groups during the first year.1 In terms of brain changes, those who came into the study with higher fitness levels saw less brain tissue loss over the years, but even those who were newer to exercise gained some degree of improved working memory, according to study co-author Asta Haberg, PhD, professor in the department of neuromedicine and movement science at Norwegian University of Science and Technology.

There was one major aspect of improvement that wasn’t related to heart rate or cortical thickness, Dr. Haberg adds—it was whether the participants felt control over their choices. For example, those who were able to choose their activity, where they exercised, and whether they exercised alone or with a training buddy tended to have more beneficial outcomes.

“Based on this, we speculate that more time spent being physically active performing an activity chosen by the individual is key to better brain health,” says Haberg. “Also, diligently following physical activity guidelines provides a significant cardiorespiratory effect in healthy older adults.”

That type of control also can be part of maintaining a regular fitness routine, previous research suggests, because it can lead to greater enjoyment with exercise. For example, one study notes that about 50% of participants in exercise programs drop out in the first 6 months, but that those who feel positive emotions tend to have significantly higher levels of program adherence.2

Why Exercise Helps the Brain

There are a number of reasons that exercise has an effect on the brain, according to Santosh Kesari, MD, PhD, neurologist and neuroscientist at Providence Saint John’s Health Center in California.

“Aerobic exercise helps with vascular integrity, which means that it improves blood flow and function, and that includes the brain,” Dr. Kesari notes. “That’s one of the reasons that being sedentary increases your risk of cognitive issues because you’re not getting optimal circulation to the parts of the brain related to functions like memory.”

He adds that exercise also can stimulate the growth of new connections in the brain, as well as reduce inflammation throughout the body. Both play a role in helping lower age-related brain health risks.

A study in Preventive Medicine found that cognitive decline is almost twice as common among adults who are inactive, compared to those who get some form of physical activity. The connection is so strong that researchers recommended the encouragement of physical activity as a public health measure for reducing dementia and Alzheimer’s disease.3

Getting Active

Although there is ample research noting that endurance training and strength training are beneficial for older adults, those who are just starting to exercise may feel less overwhelmed by recognizing that all movement is helpful.

For example, in its information about older adults and brain health, the Centers for Disease Control and Prevention (CDC) suggests activities such as dancing, walking, light yard work, gardening, and using the stairs instead of the elevator.4

It also recommends doing quick activities like squats or marching in place while watching TV. To keep increasing exercise and finding new ways to challenge yourself every week, the CDC recommends keeping a simple diary of daily activities.4

1. Pani J, Reitlo LS, Evensmoen HR, et al. Effect of 5 years of exercise intervention at different intensities on brain structure in older adults from the general population: a generation 100 substudy. CIA. 2021;Volume 16:1485-1501. doi:10.2147/CIA.S318679
2. Gjestvang C, Stensrud T, Haakstad LAH. Are changes in physical fitness, body composition and weight associated with exercise attendance and dropout among fitness club members? Longitudinal prospective study. BMJ Open. 2019;9(4):e027987. doi:10.1136/bmjopen-2018-027987
3. Omura JD, Brown DR, McGuire LC, Taylor CA, Fulton JE, Carlson SA. Cross-sectional association between physical activity level and subjective cognitive decline among US adults aged ≥45 years, 2015. Preventive Medicine. 2020;141:106279. doi:10.1016/j.ypmed.2020.106279
4. Centers for Disease Control and Prevention. Physical activity boosts brain health.