Muscle Strengthening & Brain Health
Why Resistance Training & Other Muscle Building Activities Are Good For The Brain & The Prevention of Dementia
10 Thoughts on the Muscle Brain Connection
Evolution - In the big picture of our existence, exercise or moving to improve health and fitness is a strange concept. Still, there’s no doubt that it’s essential for our physical and mental health. But why isn’t it easier for us to exercise? Why do many of us have to force ourselves? Harvard evolutionary psychologist Professor Daniel Lieberman has argued that our instinct (from our ape ancestors) is to avoid exercise. We were designed to conserve energy when we could. When we were eventually upright, we walked or ran to hunt or collect food. Or, we conserved energy. We didn’t exercise.
Amazingly Athletic Ancestors. Researchers study the skeletal differences of various athletes to assess how much demand is put on their bones. Applying this method to fossils, researchers found that the shins of Homo sapiens and Neanderthals between 40,000 and 120,000 years old “appear to be even more reinforced than those of cross-country athletes who’ve run 80 to 100 miles per week since adolescence.” Another study compared 30 Neolithic women and present-day runners, soccer players, rowers, and non-athletes. While their lower leg bones were similar to non-athletes (suggesting they stayed closer to home), their arms appeared much stronger than the rowers, who trained up to 21 hours weekly. The activities responsible for this would have been planting, harvesting crops, grinding grain, and crafting pottery….over and over again.
Sarcopenia is the progressive loss of muscle mass that occurs with aging and immobility. Though considered a geriatric problem, it is also a modern life problem. It is partly caused by oxidative stress, which occurs through the accumulation of free radicals, impairing protein synthesis and increasing the breakdown of protein, mitochondrial dysfunction, and inflammation. Ultimately, this leads to muscle cell death, muscle atrophy, and loss of muscle mass.
Sarcopenia is also caused by immobility. When we are not moving, our muscles aren’t contracting, and muscle fibers start to break down and decline in mass. The “use it or lose it” principle applies here.
Beginning at age 30, we naturally start to lose 3–5% of muscle mass per decade. If it becomes more accelerated, it can cause difficulties with daily activities like standing from a chair, walking, twisting the lid off a jar, or carrying groceries. Over time, loss of strength can lead to falls or other injuries. It is estimated that 20% of people develop sarcopenia. However, it is often not assessed and diagnosed. I think of it as a spectrum, just like any other degenerative condition in our body, including neurodegeneration.
Sarcopenia & Cognition: Sarcopenia appears to be related to cognitive decline and Alzheimer’s. Again, both are a result of tissue degeneration. The large UK-Biobank study showed that sarcopenic traits are significantly associated with lower cognitive performance and differences in brain structure in a middle-aged and older adult population.
Blood Sugar Regulation - In a previous newsletter, I discussed how Alzheimer’s is increasingly considered “Type 3 diabetes” due to evidence of a decrease in the brain’s ability to access and use glucose. Higher blood sugar has been linked not only to Alzheimer’s but also to depression.
Muscle uses glucose. Adequate muscle mass is important for blood sugar regulation and "metabolic balance.” The more muscle we have, the more glucose gets used. One round of resistance training has been found to lower blood sugar for up to 24 hours and insulin levels for up to 18 hours. Resistance training has been found to lower HbA1c (3-month blood sugar) in those at risk of Type 2 Diabetes.
Anti-Inflammatory Effects of Exercise - Exercise triggers inflammation, which affects anti-inflammatory and repair mechanisms. The overall effect is anti-inflammatory. In a previous newsletter, I addressed the 10 ways a general exercise benefits the brain, including releasing BDNF, myokines, endorphins, and neurotransmitters while promoting detoxification, lowering oxidative stress, and lowering inflammation.
Grip Strength - measures the health of the muscles of the hand and forearms. Interestingly, it is considered an indicator of overall well-being in adults - a measure of our vitality. It is typically measured using a hand-held dynamometer (in the photo above). You squeeze it with all your strength, normally three times, and an average score is obtained. For those who have access to one, this website gives averages by age.
Lower grip strength is associated with greater mortality and a greater risk of heart attack or stroke.
Grip Strength & Brain Health - Grip strength is also increasingly recognized as a risk marker for psychiatric illness and neurodegeneration in older adults. A large UK study of 40,000 participants found that “greater grip strength was associated with better cognitive functioning, higher life satisfaction, greater subjective well-being, and reduced depression and anxiety symptoms while controlling for numerous demographic, anthropometric, and socioeconomic confounders.”
Another study, which focused on those with genetic loading for Alzheimer’s with the APOe4 gene, found that those with “faster walking pace and higher handgrip strength had the lowest risk of dementia.”
One study found that knee extension muscle strength decline co-occurs with atrophy in frontal, temporal, and occipital gray matter.
Is the brain loss causing the muscle loss? Is the muscle loss causing the brain loss? Are they causing each other? Or are they both consequences of oxidative stress and inflammation?
Covering Our Bases - Remember that accelerated aging is due to oxidative stress and inflammation. Brain symptoms of any kind are a good indicator of oxidative stress.
Our genes, exposures, stressors, and lifestyle impact our vulnerability to oxidative stress. In addition to exercise and strengthening, some (if not all) of us will also need to lower our exposure to toxins, remove toxins, support our detoxification organs, support our antioxidant systems, and lower inflammation.
Building Muscle - If you’re just starting to tend to your muscles, it can help to assess your current strength. I can’t know what is safe for you, but your doctor and a trainer can. Beyond grip strength, we can use guidelines for pushups, planks, hanging from a bar, or a farmer’s carry to assess our strength.
There are endless ways to build muscle, from lifting weights, using resistance bands, or doing activities around our home, yard, or garden that involve lifting. We can also do activities using our body’s weight, such as lunges. Our legs have the largest muscles in our body. Strengthening them can yield the biggest results.
If we spend a lot of time at a desk, it can also help to break things up with some short strengthening exercises.
If we’ve been sedentary, any physical activity will start moving us in the right direction. Building slowly and listening to our body is key.
But what about the mental obstacles? How can we override our natural instinct to conserve energy, …..beyond considering the health consequences of sarcopenia? The other reason our ancestors moved was for fun. Dancing is a tradition in almost all human cultures. We, too, can become stronger and have fun doing it. We can figure out how to make strengthening and other exercise social by doing it with a friend, a group, or a trainer. We can creatively figure out what makes it interesting, practical, and sustainable for us.
Lastly, for anyone struggling to stick with their exercise goals, you might check out this previous newsletter - Mental Shifts For Sustaining Healthy Habits.
Until next time,
CourtneySnyderMD.com
Medical Disclaimer:
This newsletter is for educational purposes and not intended or implied to be a substitute for professional medical advice, diagnosis, or treatment for yourself or others, including but not limited to patients you are treating (if you are a practitioner). Consult your physician for any medical issues that you may be having.
Learned about the grip strength correlation to longevity a few years ago, and started doing pullups with a weighted vest on, which is what I am about to go do.
Also, Ive read that our ancestors walked while carrying heavy loads constantly, which explains the stronger arms.
There are a lot of people today who simulate this with rucking. Hiking with a weighted pack or vest. You get cardio and strength training at the same time, and its easier on the joints than running.
However, I imagine its better for the arms to physically carry something in them, rather than strap it on. Michael Easter is the rucking guru, and hes on Substack.