High-intensity interval training (HIIT) improves function in older adults significantly better than moderate-intensity continuous training (MICT) at a steady level of exertion, according to a new study from McMaster University. These findings were published on October 30 in the journal Applied Physiology, , and Metabolism.

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Over the past decade, countless studies have documented a correlation between aerobic physical activity and better brain function. However, researchers are still trying to figure out exactly how long (duration) and hard (exertion) someone needs to exercise to optimize brainpower and cognitive function.

Another HIIT-related paper (Klein et al., 2019) from earlier this year by researchers at the University of Queensland in Australia speculates that interval training may offset cognitive decline by boosting cerebral blood flow (CBF).

The latest HIIT training research (2019) from McMaster University reaffirms that aerobic intensity may be key to optimizing memory performance via physical activity.

For their most recent study, Jennifer Heisz and colleagues in the Department of Kinesiology and their partners at the McMaster Physical Activity Centre of Excellence (PACE) recruited dozens of healthy (but sedentary) seniors between the ages of 60 and 88.

At the outset of this Canada-based study, each participant had their high-interference memory assessed using a "Mnemonic Similarity" task and performed a "Go Nogo" and "Flanker" task to establish a baseline reference for executive function.

Then, study participants were divided into three groups that each performed different workouts: 1) high-intensity interval training (HIIT), 2) moderate-intensity continuous training (MICT), or 3) stretching only (Control Group).

Those in the HIIT group did four sets of high-intensity walking on a treadmill for four minutes, followed by a recovery period and repeated. The MICT group performed one set of moderate-intensity treadmill walking for about 45 minutes. The control group workout was limited to stretching only.

Notably, participants in the HIIT group improved their high-interference memory performance by up to 30 percent. On average, participants in the MICT group and stretching only control group did not improve their memory performance.

Interestingly, exercise intensity seemed to matter less when it came to improving overall ; positive trends in this cognitive domain were observed after both HIIT and MICT.

"It's never too late to get the brain health benefits of being physically active, but if you are starting late and want to see results fast, our research suggests you may need to increase the intensity of your exercise," Heisz said in a news release. "This work will help to inform the public on exercise prescriptions for brain health so they know exactly what types of exercises boost memory and keep at bay."

Heisz cautions that it's critical for individuals to tailor any high-intensity interval training to match current fitness levels. From a practical standpoint, she recommends adding some intensity to a walking program by increasing the incline of a treadmill, finding a place with hills to walk, or increasing your pace between alternating street lamps.

Another recent HIIT study (Masuki et al., 2019) from the Institute for Biomedical Sciences at Shinshu University in Japan found that interval walking training (IWT) improves fitness and health in elderly individuals. According to the recent Hiesz et al. research: "Improvement in fitness correlates with improvement in memory performance."

The new study from Japan also offers some detailed prescriptive advice. For their IWT study, the researchers defined "Interval Walking Training" as walking at 70 percent of the walker's peak aerobic capacity (VO2 Max) for three minutes, followed by three minutes at 40 percent of their VO2 capacity. This six-minute cycle of intervals is repeated for five sets (or more).

In conclusion, Jennifer Heisz said: "Exercise is a promising intervention for delaying the onset of dementia. However, guidelines for effective prevention do not exist. Our hope is this research will help form those guidelines."

Aerobic intensity plays a role in optimizing the neuroprotective and memory-boosting power of cardiovascular workouts. However, much more rigorous scientific research is needed to dial in on the exact dose-response that benefits various cognitive functions and memory capacity across a lifespan.

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