If you've been working on keeping your memory fit and stave off dementia by doing puzzles and other mental exercises, you may want to try another kind of memory booster — physical exercise.

High Intensity Interval Training or HIIT workouts do more than keep our hearts healthy and bodies fit, according to a new study. This type of physical exertion keeps our hippocampus — the area of the brain responsible for memory — in good shape and increases brain volume.

Moderate-intensity workouts were made up of 30 minutes of brisk walking on a treadmill.

What's more, the benefits lasted up to five years, showing that HIIT can help to preserve our brains throughout our lives.

Researchers from the University of Queensland in Australia kept track of 194 older adults between the ages of 65 and 85 who had no signs of cognitive decline. Each person was assigned to either a 6-month program that used low-intensity exercise, moderate-intensity exercise or HIIT. Each participant engaged in three workouts every week.

The low-intensity workouts consisted of stretching, balance and relaxation. The moderate-intensity workouts were made up of 30 minutes of brisk walking on a treadmill. The HIIT sessions were also performed on a treadmill. But in addition, these participants completed a four-minute round of hard exercise (at around 80-95 percent of their maximum heart rate) broken up with three minutes of recovery between. This was repeated four times.

Following six months of one of the three routines, participants were given a task designed to test their memories. People in the HIIT group made fewer mistakes on the tasks compared to either the low-intensity or the moderate-intensity folks.

When the participants were given the same memory test again five years later, the HIIT group still did better than the other groups. With MRI brain scans of the participants, the researchers also saw that the HIIT workout group had less age-related shrinkage of their brain volume. In particular, the hippocampus was better preserved.

“This is the first study to our knowledge to identify that a HIIT paradigm for the healthy elderly is suitable and effective at significantly improving and retaining long-term hippocampal-dependent learning for up to five years,” the researchers said.

“The improvement and long-term retention of hippocampal learning ability following HIIT exercise provides a new insight into how the elderly could be insulated from cognitive decline even though their exercise capabilities may decline with advanced age,” they added. “This approach could greatly enhance the capacity for clinicians to tailor personalized exercise programs, including those at risk for cognitive decline.”

The study did have a few limitations. For example, it wasn't designed to determine if the duration of the HIIT interval or the number of intervals performed in each session matter more when it comes to brain health benefits. This will be something future research needs to investigate.

The research also only looked at people who showed no signs of cognitive decline. It's unclear whether high intensity exercise would benefit people who already have cognitive decline.

You needn't invest in expensive equipment or go to a gym to get started. Since the primary goal of HIIT is to elevate your heart rate and push your body, you can choose to do simple exercises at home. Climb stairs, do repetitive body squats, clapping push-ups, lunges and jumping jacks. Take a brisk uphill walk or jog — anything that gets your heart pumping.

There's little doubt that HIIT has health benefits, but before you begin any new workout routine, especially a rigorous one like HIIT, it's crucial that you first consult your healthcare provider.

The study is published in Journal of Aging and Disease.