Leg Power Equals Brain Power

by Nina

Bhavani Cooper, Age 56

“Leg power predicts both cognitive ageing and global brain structure, despite controlling for common genetics and early life environment shared by twins. Interventions targeted to improve leg power in the long term may help reach a universal goal of healthy cognitive ageing.” —Steves, CJ, et al.

I have to say that even I always repeat to myself what Ram wrote about the brain “what is good for the heart is good for the brain,” I am so used to thinking about the brain as somehow being separate from the rest of the body, I was flabbergasted to read about a recent study of aging twins that showed that powerful leg muscles resulting from physical exercise correlates with sharper minds. Yes, even though the brain is just another organ in your body, like your heart or your liver, we’re so used to being told that doing mental exercises, like, God forbid, crossword puzzles, is the best way to keep our brains healthy as we age, that is hard for a lot of us—me included—to take in that something like doing yoga standing poses could actually be much more effective.

In a recent study Kicking Back Cognitive Ageing: Leg Power Predicts Cognitive Ageing after Ten Years in Older Female Twins. scientists at Kings College London set out to test whether muscle fitness (measured by leg power, since the thigh muscles are the largest muscles in the body) could “predict cognitive change” in a healthy older population over a 10-year time interval. Twins were used in the study so genetic factors could be ruled out. And leg strength was measured as a more objective indicator of exercise patterns than self-reporting (since self-reporting is notoriously unreliable). 

The study was performed on 324 female twins (average age 55, range from 43-73) at two time points ten years apart. The scientists performed cognitive testing on all the study participants, and for 20 pairs of identical twins, they also conducted brain-imaging scans. According to the New York Times, the scientists found that those who had had the sturdiest legs a decade ago showed the least fall-off in thinking skills, even when scientists controlled for factors such as fatty diets, high blood pressure, and shaky blood-sugar control. The Times reported that the differences in thinking skills were particularly striking within twin pairs:

“If one twin had been more powerful than the other 10 years before, she tended to be a much better thinker now. In fact, on average, a muscularly powerful twin now performed about 18 percent better on memory and other cognitive tests than her weaker sister.

“Similarly, in the brain imaging of the identical twins, if one genetically identical twin had had sturdier legs than the other at the start of the study, she now displayed significantly more brain volume and fewer “empty spaces in the brain” than her weaker sister.”

So this is very dramatic evidence about how important exercise is for maintaining cognitive health! The funny thing is that even the main author, of the study, Dr. Steves, was surprised by the results. The New York Times quoted her:

“I was quite surprised by the strength of the findings,” Dr. Steves said, “because to be honest, I am someone who has always in the past prioritized work of the mind over work of the body. This study brings home to me that the brain needs exercise to keep fit.”

For more information about the study, see Brawn and Brains (only the abstract for the study is available to general public).

Now we’ve been recommending exercise in general for cognitive health for some time now (see 6 Ways to Foster Brain Health with Yoga and Featured Sequence: Brain Health Practice). But if you’re interested in working on leg strength in your yoga practice, my post The Importance of Yoga for Strength had some basic recommendations for lower body strength. In general, though, the following are strengthening for your legs:

• Standing poses where you stand one or two bent knees, such as Powerful pose (Utkatasana), Warrior 2 pose (Virabradrasana 1), Extended Side Angle pose (Utthita Parsvakonasana), and Lunge pose 
• Standing poses where you balance on one leg, such as Tree pose (Vrksasana), Half Moon pose (Arda Chandrasana), and Warrior 3 pose (Virabradrasana 3)
• Backbends where you lift your legs up away from the floor, such as Locus pose (Salabasana) and Hunting Dog pose
• Stretching poses for your legs, such as Reclined Leg Stretch (remember, stretching is also strengthening—see Just Stretching is Not Just Stretching)

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