Áine Kelly, professor in physiology at the Trinity College Dublin, shares insights on the benefits of exercise for our memory, blood vessels and immune system.
Regular exercise changes the structure of our bodies’ tissues in obvious ways, such as reducing the size of fat stores and increasing muscle mass. Less visible, but perhaps even more important, is the profound influence exercise has on the structure of our brains – an influence that can protect and preserve brain health and function throughout life. In fact, some experts believe that the human brain may depend on regular physical activity to function optimally throughout our lifetime.
Many studies suggest that exercise can help protect our memory as we age. This is because exercise has been shown to prevent the loss of total brain volume (which can lead to lower cognitive function), as well as preventing shrinkage in specific brain regions associated with memory. Another study showed that shrinkage of the hippocampus (a brain region essential for learning and memory) in older people can be reversed by regular walking.
The brain is highly dependent on blood flow, receiving approximately 15% of the body’s entire supply – despite being only 2-3% of our body’s total mass. This is because our nervous tissues need a constant supply of oxygen to function and survive. When neurons become more active, blood flow in the region where these neurons are located increases to meet demand. As such, maintaining a healthy brain depends on maintaining a healthy network of blood vessels.
Regular exercise increases the growth of new blood vessels in the brain regions where neurogenesis occurs, providing the increased blood supply that supports the development of these new neurons. Exercise also improves the health and function of existing blood vessels, ensuring that brain tissue consistently receives adequate blood supply to meet its needs and preserve its function.
Recently, a growing body of research has centred on microglia, which are the resident immune cells of the brain. Their main function is to constantly check the brain for potential threats from microbes or dying or damaged cells, and to clear any damage they find.
But recently, we’ve shown that exercise can reprogramme these microglia in the aged brain. Exercise was shown to make the microglia more energy efficient and capable of counteracting neuroinflammatory changes that impair brain function. Exercise can also modulate neuroinflammation in degenerative conditions like Alzheimer’s disease and multiple sclerosis. This shows us the effects of physical activity on immune function may be an important target for therapy and disease prevention.