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But did you know cardio may severely decrease your risk of dementia? That's the finding of a new study published in the journal Neurology.

The study found that women with high stamina had an 88 percent lower risk of dementia than women who were moderately fit. Researchers first rated a group of women on their fitness via an ergometer cycling test in 1968, and tested them six more times over the next 44 years, also examining their brain health. High fitness, in this study, was determined by cardiovascular condition. People who weren't fatigued after a working time of six minutes in the cycling test gradually had their workload increased until they reached their limit of exhaustion—dubbed "peak workload" by the scientists involved.

While all levels of increased fitness experienced reduced risk for dementia, the most pronounced risk reduction was among women with the highest fitness.

One in 10 people ages 65 and older has Alzheimer's dementia (the most common form of dementia, accounting for 60 to 80 percent of cases), and nearly two-thirds of Americans with Alzheimer's are women, according to the Alzheimer's Association. By 2050, the number of people 65 and older with Alzheimer's dementia may nearly triple, from 5.3 million to 13.8 million, says Keith Fargo, Ph.D., director of scientific programs and outreach for the Alzheimer's Association.

However, research like this Neurology study—along with a two-year clinical trial by the Alzheimer's Association currently underway, testing whether lifestyle interventions including physical activity can protect cognitive function in older adults—are efforts toward reversing this trend.

"Growing evidence indicates that people can reduce their risk of cognitive decline by adopting key lifestyle habits, like getting regular physical activity, eating a brain-healthy diet, staying socially connected, getting enough sleep, and challenging and activating their mind," says Fargo.

How then, exactly, do you reach that point of high stamina, or enduring strength? By training harder. Gradually increase the difficulty of your workouts by incorporating intense HIIT sessions several times a week, and opt for interval training over steady-state cardio. Even better? Combine strength sessions with cardio to challenge your cardiovascular system. (Psst—more tips for making your cardio workout harder.)

When it comes to lifting weights, decrease the amount of rest time between sets to keep your heart rate elevated. Opt for compound movements over isolated ones to improve your endurance. And while your daily gym habit is good, remember it's important to break out of your routine once in a while. Switch up the time you go, the class you take, the order you typically follow to challenge both your body and your mind to work differently.

Any study that may give someone the jolt they need to get healthier is worth reading, in our book. But Demetrius M. Maraganore, M.D., FAAN, chairman of the department of neurology and co-director of NorthShore University HealthSystem's Neurological Institute in Chicago, notes the results from this observational study should be interpreted with caution, as only 191 women were included in the exercise subsample. "Small sample sizes tend to exaggerate the magnitude of the effect," he says.

Still, the key takeaway here is that "dementia, including Alzheimer's disease, is preventable, and that an ounce of prevention is worth a pound of cure," says Dr. Maraganore.

{originally produced for Shape.com}