Now that Canada’s all-too-brief beach season has come to an end once again, you might be tempted to push the dumbbells to the back of your closet, to ditch the vanity, forget about bulging muscles, and focus instead on full-body aerobic fitness. this is closely linked to health and longevity.
But a recent study by McGill University researchers, published in the journal JAMA Network Open, offers a new reason to keep working on building muscle: It’s good for the brain, not just the biceps. The results suggest that greater muscle mass helps prevent cognitive decline in older adults beyond what would be expected based on their exercise levels.
The findings are drawn from more than 8,000 older adults from the Canadian Longitudinal Study of Aging, with an average age of 73. They underwent a series of baseline assessments that included an X-ray measurement of their muscle mass, a battery of 10 cognitive tests. and questionnaires about their exercise habits and other health characteristics. The cognitive tests were repeated three years later.
At baseline, approximately one-fifth of the subjects met predefined criteria for low muscle mass. Over the next three years, compared to those with normal muscle mass, these subjects experienced a steeper decline in reaction times and executive function, the cognitive skills that allow you to plan, focus attention and prioritize your actions .
Do you want strong muscles? Eat your green leafy vegetables
On the surface, these results are not surprising. After all, says Stéphanie Chevalier, a professor in McGill’s School of Human Nutrition and lead author of the study, previous studies have found that low strength and lack of physical activity predict faster cognitive decline. But there’s a difference between using muscle and simply having it.
“The question we asked in our study is: when we consider strength and physical activity, does muscle mass have an independent predictive role in cognitive decline?” explains Dr. Chevalier.
Using statistical techniques, the researchers were able to compare subjects with equivalent muscle strength, as assessed by a handgrip test, and equivalent exercise habits. Indeed, those with lower muscle mass still had a faster subsequent decline in executive function, suggesting that muscle tissue itself has some kind of neuroprotective function.
Figuring out exactly how muscle helps the brain remains a challenge. There are many indirect links: those with more muscle are generally more active, which can help keep oxygen-rich blood flowing to the brain, for example.
But Dr. Chevalier’s results suggest that there may also be more direct mechanisms. One possibility is the role of myokines, a set of hormone-like molecules produced by muscle cells that can travel to the brain and influence mood, learning and other cognitive functions. Greater muscle mass can also help control blood glucose levels, protecting the brain from damage.
This is not to suggest that strength training is the only way to improve brain health. A 2014 study that followed 150,000 walkers and runners over a 17-year period found that meeting the standard recommendation of 150 minutes of moderate aerobic exercise per week was associated with a 25% reduction in the likelihood of developing Alzheimer’s disease. And those who exercised twice as much had a 40 percent reduced risk.
So if you want to cover all your bases, choosing between cardio and weights is easy: do both. Incorporate some resistance training into your routine a few times a week. You don’t necessarily need to lift heavy weights, but press enough that your effort is at least eight out of 10 at the end of each set.
Also, Dr. Chevalier adds, make sure you eat a good diet with enough protein, ideally spread throughout the day rather than concentrating on a massive protein bomb at dinner. There is evidence that older adults become less responsive to protein’s muscle-building stimulus, so aim for about 0.4 grams of protein per kilogram of body weight with each meal. For someone who weighs 150 pounds, that equates to 27 grams of protein, the equivalent of a tuna sandwich, a glass of milk and a handful of almonds.
And remember, the goal isn’t to wow everyone at the beach next year yet. A more realistic goal for older adults is to keep the muscle you have and avoid further loss, says Dr. Chevalier, citing the one law of exercise no one disputes: “Use it or lose it.”
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Alex Hutchinson is the author of Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance. Follow him on Twitter @sweatscience.