In recent years, dozens of studies have reported the neuroprotective benefits of aerobic exercise. However, the dose-specific amount and intensity of physical activity necessary to safeguard cognitive function as your body and brain get older has been up for debate.

Yesterday, a new longitudinal study from Finland—that followed 3050 twins for 25 years—reported that moderately-vigorous physical activity (i.e., jogging slowly) throughout midlife is associated with better cognition in old age.

The September 2016 study, “Midlife Physical Activity and Cognition Later in Life: A Prospective Twin Study,” appears in the Journal of Alzheimer's Disease.

The Finnish Twin Cohort study found that the cognitive benefits of moderately vigorous physical activity in midlife is statistically independent of other midlife factors such as hypertension, smoking, binge drinking, education level, gender, and obesity. 

According to this study, the most important factor regarding brain health and fitness wasn't how much exercise someone did, but simply that he or she avoided sedentarism and chronic inactivity. Sedentarism is described as, "prolonged periods of sitting or overall inactivity which exacerbates health risks associated with a lack of dedicated exercise." The bottom line appears to be that doing something (anything!) physically active on a regular basis helps keep your mind sharp in old age.

How Much Mid-Life Exercise Do You Need to Protect Cognition in Old Age?

In terms of the optimum volume of physical activity that benefits cognition, the percentile of individuals who were the most active did have a greater reduction in their risk of cognitive decline compared with those in the most sedentary percentile.

That said, the researchers emphasize that although vigorous midlife physical activity was associated with less cognitive impairment, there wasn’t a clearly defined dose-response association between increasing the volume of physical activity and someone's risk of cognitive impairment.

The researchers identified the sweet spot of moderately-vigorous physical activity by keeping tabs on the exercise habits of all individuals in the study and then compared the cognitive function in twin pairs where one twin had been more physically active than the other.

Most interestingly, dramatically increasing the volume of physical activity was not associated with increased memory-protective benefits. Instead, the researchers found that a moderate amount of slightly vigorous physical activity was sufficient to stimulate memory-protecting benefits. Across the board, the chronically sedentary and inactive group of twins stood out statistically as having a significantly higher risk for cognitive impairment.

Small Amounts of Exercise Have Huge Neuroprotective Benefits

If you are physically inactive, hopefully, this study will motivate you to start being more physically active. Even if you hate to exercise, the good news is that small amounts of physical activity will pay huge neuroprotective dividends. Of course, being active also reduces morbidity and increases longevity.

This study doesn't give a prescriptive recommendation for a tonic level of physical activity in midlife that will protect your cognitive abilities as you age. However, other studies have found that for older adults, doing as little as 75 minutes of moderately-vigorous exercise per week has significant health benefits.

Based on my life experience as a coach and personal trainer, I'm reluctant to give any rigid recommendations regarding the weekly duration of exercise that is ideal for your psychological and cerebral well-being.

When I was younger, exercising for hours every day was a labor of love that I don't regret. But, overtraining took a heavy toll on my mind and body. I always knew intuitively that pushing myself too hard and grinding my body into the ground day after day wasn't "good for my health." It's nice to have empirical evidence confirm that when it comes to exercise, more is not necessarily better.

Please use common sense when structuring your daily and weekly exercise regimen. Find an activity that you enjoy doing. Listen to your body and gut instincts to find a tonic level that makes you feel good. If you have a tendency to be compulsive, neurotic, or are an "obligatory exerciser" remember that excessive amounts of exercise can backfire. Practice exercise moderation and maintain life balance by finding your personal sweet spot between being a couch potato and an exercise fanatic.

Although no cure for dementia currently exists, a wide range of research from the past decade affirms the neuroprotective benefits of aerobic exercise. But, exercise alone is never going to be a panacea for preventing dementia.

Yes, moderately-vigorous physical activity can reduce your risk of dementia. Nonetheless, each of us should take a multi-pronged approach to keep your brain healthy and your mind sharp right here, right now—and as a prophylaxis for cognitive decline in the future. 

Consistently keeping all four brain hemispheres stimulated is key to maintaining a sound mind in a sound body as you age. Daily activities such as: challenging yourself cerebrally, pushing your creative capacity, engaging in thought-provoking conversation, exposing yourself to enriched environments, mastering new skills, and exploring uncharted physical and psychological domains will all benefit your cognitive function today, and as you get older.

https://www.psychologytoday.com/blog/the-athletes-way/201609/study-more-exercise-isnt-necessarily-better-your-brain