Weak muscles, weak brain? True or not? Iโve always been more concerned with my mental state than my fitness level. Maybe thatโs because Iโve battled with some gene mutations that mess with my mood, motivation, and energy. I mean, who wants to think about fitness when theyโre struggling to stay awake and motivated?
Or maybe itโs because I love learning and exploring new ideas, and I want to keep doing that for the rest of my life.
Whatever the reason, I tend to see my brain as more important than my body. So you can imagine how shocked I was when I learned that, as I get older, the health of my muscles can have a major influence on the health of my brain.
I didnโt want to believe it, but itโs true.
Weak muscles and brain connection
Our brain and muscles are more strongly connected than most people realize. Not only does the health of our muscles directly influence the health of our brain, but the two are also affected by many of the same factors.
When our muscles contract, they produce small proteins called myokines, many of which are involved in communication between the muscles and the brain. Releasing them during exercise is of great benefit to the brain and may be especially critical in maintaining cognitive ability as we age (1).
IL-6 (interleukin-6, a cytokine) is also released during exercise; the amounts increase with intensity and duration. According to Docherty et. al (2022), IL-6 usually increases inflammation โ but it has the opposite effect during exercise. Here it stimulates the anti-inflammatory cytokines IL-10 and IL-1Ra and inhibits TNF-ฮฑ, a pro-inflammatory cytokine released in response to cellular damage (2).
The tole of BNDF
These cytokines can cross the blood-brain barrier and reduce immune inflammatory responses, which are known to play a role in neurodegenerative disorders.
Our muscles also secrete something you may be more familiar with. BDNF (brain-derived neurotrophic factor) plays a role in memory consolidation, cognitive function, and neuron protection. It also decreases the production of amyloid plaques (3). People with Alzheimerโs, Parkinsonโs disease, and depression tend to have low levels of BDNF (3).
So how do we generate more BDNF?
Exercise for Your Muscles and Brain
As you would expect, exercise is a fantastic way to increase BDNF, but not only because of its effect on myokines and other cytokines.
Our muscles play an important role in glucose storage and metabolism. Low muscle mass is associated with insulin resistance, which is an independent risk factor for cognitive decline (4). Exercise protects against insulin resistance by stimulating energy metabolism in the brain as well as the rest of the body (5).
Physical activity also promotes mitochondrial health, reduces excessive oxidative stress, and improves ATP production in both the muscles and the brain (5). These improvements all help to prevent cognitive dysfunction (5).
Exercise as medicine
Exercise also supports our microglia, the cells that regulate brain development, and the maintenance and repair of neurons. These cells also play a key role in the elimination of abnormal proteins involved in neurodegenerative diseases.
Exercise may also protect the neurons by keeping the intestinal barrier intact, preventing toxins from reaching the brain.
Studies have shown that regular physical activity and improving weak muscles, can reduce the risk of both cognitive decline and dementia (by 38% and 28% respectively) (6). Combining aerobic exercise (like dancing, cycling, and sports) with weight-bearing exercise can keep your muscles from shrinking and improve cognitive skills like memory and reasoning (6).
But exercise shouldnโt be the only tool in your toolbox. The right nutrition can also enable your muscles to better support your brain.
Nutrients for your weak muscles
We need protein to build, repair, and maintain our muscles when weโre young. But as we age, our muscles start to shrink. According to Oudbier et al. (2022), muscle mass declines at a rate of approximately 3%โ8% per decade after the age of 30 and accelerates from 60 years onwards (7). This means we require even more protein as the years go by.
And protein doesnโt just support the muscles; itโs directly involved in cognitive functions. Low protein levels in the brain accelerate its degeneration and impair memory.
A study funded by the National Institutes of Health (8) suggests that an over-the-counter supplement known as HMB (beta-hydroxy beta-methylbutyrate) may also help. Bodybuilders use HMB to improve their performance and increase the benefits of exercise, including gains in muscle size and strength. It reduced plaques and increased factors for neuronal growth in mice with Alzheimerโs disease, which is promising. Hopefully, human studies of HMB and other supplements will follow.
Help Your Muscles Help Your Brain
With more and more people over the age of 60 succumbing to neurodegenerative diseases like Alzheimerโs, itโs easy to feel helpless. But there are plenty of things you can do to protect your brain. Who knew that looking after your muscles would be near the top of the list? So yes, weak muscles can mean a weak brain. And there is always time to do something about that!
