Exercise is widely regarded as a cure-all for our bodies and brains – so much so that the U.S. Department of Health and Human Services outlines standards for physical activity: at least 150-300 minutes of moderate-intensity physical activity a week or 75-150 minutes of vigorous aerobic physical activity in addition to muscle-strengthening activities of moderate intensity per week. And, for older populations, as many aerobic and muscle strengthening activities as manageable are advised. However, most of these guidelines focus narrowly on physical outcomes, saying little about how exercise improves brain health.
A growing body of research has suggested a connection between physical exercise and improved cognition, particularly during aging. Formally, exercise refers to any planned and structured activity that is voluntarily aimed at improving and/or maintaining physical fitness; whereas physical activity (PA) is any/all movements that require activity of our skeletal muscles and energy expenditure. It is important to understand this distinction in this topic. Exercise is not only a form of physical activity, but one that also requires planning, structure, and repetition.
Habitual exercise has been known to reduce body mass index, improve cardiorespiratory fitness, and has even been coined as an anti-inflammatory ‘drug’ in diseases like Type 2 Diabetes and cardiovascular diseases. Most recent research has pivoted to focus on exercise’s impact on brain plasticity– the ability to reorganize the brain’s functions, structure, and neural connections in response to internal and external stimuli. Particularly, research done by neuroscientists Carl Cotman and Nicole Berchtold reveal that voluntary exercise increases levels of brain-derived neurotrophic factor (BDNF), a protein that helps nerve cells grow, mature, and survive. BDNF is especially active in the hippocampus – the brain region responsible for learning and memory.
When we exercise, our muscles contract and our heart rate elevates. These physiological changes trigger a surge in BDNF and neuroplasticity. Our working muscles release myokines and exerkines into the bloodstream. These molecules travel to the brain to reduce inflammation and stimulate neuronal growth. One of the more immediate effects of exercise on the brain is the increased release of neurotransmitters, particularly dopamine, serotonin, and endorphins while lowering stress hormones like cortisol.
More broadly, your brain responds to movement similar to the way your muscles do: it adapts and strengthens with consistent use. In addition to the molecular pathway discussed above, physical exercise has been proven to show expanded brain volumes in:
- Gray matter, which helps the brain process data
- White matter, which links different regions of the brain together
- Hippocampus, which plays a critical role in memory functions
Whether it’s a 15-minute walk through your neighborhood or a structured workout class, movement of almost any kind can help keep your brain sharp and resilient.