Exercise Is a Double-Edged Sword—Too Much Makes You Dumber
“Life lies in movement”—it shapes our strong bodies and enhances resistance to illness. Yet, for humans, there is a limit to exercise. Exceeding this limit may not benefit but actually harm us.
U.S. neuroscientist Justin Rhodes found in his research that mice addicted to exercise exhibited slower brain responses than normal-exercising mice. This report was published in journals such as "Neuroscience" and "Behavioral Neuroscience." Rhodes concluded, “While exercise benefits the brain, moderation is key.”
Moderate Exercise Makes You Smarter
On the side of the human brain lies a structure resembling a hippocampus—the hippocampus, responsible for learning and memory.
Researchers at the Salk Institute in La Jolla, California, discovered through animal experiments that rats enjoying running on wheels developed new cells in their hippocampi, whereas rats confined to ordinary cages did not.
Thus, researchers believe that regular, moderate exercise enables humans to grow more cells in the hippocampus, enhancing thinking, sensation, and reaction speed, making people smarter.
Excessive Exercise Makes Your Brain Dumber
Intense exercise can impair brain function through multiple pathways. Depletion of ATP energy stores during exercise may be the main reason for reduced central nervous system function. During exercise, blood redistribution, accumulation of free radicals, vascular endothelial damage due to accelerated blood flow, and buildup of acidic metabolites reduce cerebral blood and oxygen supply, directly suppressing neural activity and impairing brain function.
Studies show that short-term intense exercise reduces cortical activity, while prolonged intense exercise lowers widespread brain tissue excitability.
In daily life, people often feel mentally sluggish and physically slow after vigorous exercise—this relates not only to the above factors but also to the body’s own “protective inhibition” mechanism.
During excessive exercise, massive energy depletion triggers protective inhibition to prevent further energy loss. People feel extreme fatigue, weakness, and slowed mental response. Long-term excessive exercise reduces the sensitivity of this protective mechanism, damaging brain function. Symptoms include poor concentration, insomnia, forgetfulness, and long-term harm to overall health.
Find the Right Exercise Volume
The standard for appropriate exercise is heart rate—60% to 85% of maximum heart rate. Note that due to individual differences, the difference from resting heart rate should be 15% to 30%, or even more. Therefore, optimal exercise volume must be determined based on age, gender, occupation, physical condition, health level, fitness background, living environment, and goals.
To check if exercise volume is suitable, observe post-exercise reactions. For example, monitor sweat production and ease of movement. Also pay attention to appetite, sleep quality, and whether you still feel motivated to exercise the next day.
Generally, older adults can focus more on hand-only aerobic exercises under aerobic conditions to enhance coordination. Children should engage in mechanical activities like stacking blocks—seemingly simple, yet they greatly promote brain development and hand-eye coordination.
Crucially, manage exercise intensity: keep heart rate within a proper range and maintain a strong time awareness. Generally, aerobic exercise sessions lasting 30 to 60 minutes are ideal. Exceeding this duration provides no benefit and may harm bodily functions.