Strength training helps brain shrink

Let me first clarify the most easily misunderstood point: the "brain atrophy" in the title of this article is completely different from the pathological brain atrophy caused by diseases such as Alzheimer's disease and accompanied by a comprehensive decline in cognitive function. The current general consensus in the academic community is that regular moderate-intensity strength training will trigger the brain's synaptic pruning mechanism, selectively reduce redundant and ineffective neural connections, and greatly improve the efficiency of neural signal transmission. This change similar to "brain slimming" will show a reduction in the size of specific brain areas in imaging testing, which is what we call "benign atrophy", which is essentially the optimization of brain function.

In 2023, the Department of Exercise Science at the University of Tsukuba in Japan conducted a small-scale controlled trial. They found 60 20-30-year-old office workers who did not exercise at all. They were randomly divided into two groups. One group took time twice a week to do 40 minutes of moderate-intensity strength training, which included the basics of squats, dumbbell bench presses, and deadlifts. The other group only did static stretching for the same length of time, and their brain MRI and cognitive abilities were retested 6 months later. The results were quite interesting: the gray matter volume of the prefrontal cortex of the strength training group shrank by 1.7% on average, but their working memory test and multi-threaded task processing scores were more than 12% higher than those of the control group.

When I first saw this study, I was stunned for a moment. Then I thought of Lao Zhou, who has been training with me in the gym for almost three years. He is an Internet project manager. He used to complain to me that I wanted to smash the computer when I was running three projects at the same time. He had to post sticky notes all over the monitor to write down requirements. In the past two years, His fitness frequency is three times a week. Last month, he told me over dinner that he could handle five projects at the same time clearly. He even used Post-it notes less. In the past, I always thought it was through strength training that he developed patience. Now it seems that his brain is "thin". There are fewer useless distractions, and he is naturally more efficient.

Of course, this conclusion is not ironclad in the academic world. One group of scholars believes that this is not atrophy caused by synaptic pruning, but that the blood flow distribution pattern of the brain changes after strength training. In the past, the prefrontal lobe had many idle capillaries supplying blood in the resting state. Now strength training requires more blood flow to the motor cortex and muscles. The idle blood vessels in the prefrontal lobe shrink, and the changes in gray value scanned by MRI are misjudged as volume reduction. In fact, the total number of neural connections is not reduced at all, but the energy supply has become more "calculated". Some more conservative scholars say that the current test samples are all young people aged 20-30, whose brains have strong neuroplasticity. If they are replaced by elderly people over 60 years old, whether strength training will trigger this pruning or delay pathological brain atrophy, there is currently not a large enough sample size to support it, and it cannot be generalized.

I have been practicing strength training myself for more than two years. I train three times a week, one for legs, one for pushing, and one for pulling. The biggest feeling is not that my memory has improved, but that I have fewer distracting thoughts. When I used to write a plan at work, I couldn't help but reach for my phone to scroll through short videos twice after writing two lines. I wandered around all morning and didn't write many words. Now when I sit down to write the next day after practicing my legs, I often realize that I have been writing continuously for almost two hours without even touching my phone. I read a popular neurological science article before and said that those fleeting distracting thoughts and useless fragmented information are actually the discharge of scattered weak nerve connections in the brain. Strength training should "cut" all these messy weak connections, which is equivalent to clearing the cache of the brain and naturally running faster.

Last year, my sister was preparing to take the postgraduate entrance examination. She couldn't sit still after half an hour of studying at home. She always wanted to eat and check her mobile phone. I forced her to go to the gym with me two nights a week to practice for 40 minutes. She just did simple movements such as glute bridges, dumbbell shoulder presses, and bent-over rowing. The weights don't need to be heavy, just standard movements. After practicing for about a month, she told me that now she can sit and memorize politics for two hours without feeling tired, and she no longer wants to touch her mobile phone. She thought it was because her willpower suddenly became stronger. I joked with her and said that you have lost weight in your brain, and the neural pathways that make you want to touch your mobile phone have been eliminated.

By saying all this, I don’t mean to praise strength training as a god. Don’t expect to remember it immediately after practicing bench press for two days. Don't panic when you see the word "atrophy". Pathological brain atrophy is brain-wide, and it will make you less able to remember things and slow down your reactions. It is completely different from the shrinkage of specific brain areas caused by strength training and accompanied by the improvement of cognitive abilities. As for the controversies in the academic circles, it is actually not that important to us ordinary fitness enthusiasts. After practicing, it is enough to feel comfortable, have a clear mind, and be efficient at work.