The benefits of sport on health

Practicing regular physical activity strengthens our body, reduces the risk of many diseases, and improves our morale. But by what mechanisms?

Exercising is good for your health. No doubt, since this “truth” is regularly reminded of us. But why? Why would regular physical activity improve our health and keep us fit? Before explaining why, let's remember that various studies have shown, among other things, that moving regularly reduces the risk of developing diabetes, dying of a stroke or heart attack, prevents certain cancers, improves morale, strengthens bones, strengthens muscles, increases respiratory capacity, reduces the risk of falls and fractures in the elderly, helps control excess weight, etc.!

In recent years, research in this area has exploded, further extending these observations. Among other things, the exercise would stimulate the brain – and especially the ability to carry out tasks that require attention, organization, planning – and reduce the symptoms of depression and anxiety in some people. In addition, biologists are beginning to understand the mechanisms triggered at the cellular and molecular level by regular physical activity.

150 minutes of moderate activity per week

Studies are also conducted to find out how the various systems of the body cardiovascular, digestive, endocrine, nervous, etc. are modified by physical exercise. They suggest that the benefits would result from a small improvement in many physiological aspects and not from a large effect limited to a few biological processes.

We also realized that you don't have to be a triathlon fan to reap the benefits of physical exercise. Twenty years ago, experts in preventive medicine advocated only intense activity. Today, they also insist on the benefits of regular and moderate sessions. One of us (JoAnn Manson) has been instrumental in demonstrating the comparable health benefits of light and heavy exercise in large-scale studies. Conducted from 1976 to 1989, these studies, carried out on 238,000 volunteer nurses, are among the largest conducted on the factors influencing women's health. Based on their data and others, the World Health Organization's latest physical exercise guidelines, published in 2010, recommend at least two and a half hours of moderate activity per week (walking fast, for example) or an hour and a quarter of vigorous endurance activity, such as jogging, once a week, as well as muscle-strengthening exercises at least two days a week.

Let's take a look at some of these discoveries and the multiple ways in which physical exercise protects and maintains the body. But first, let's recall how the body reacts to increased physical activity. Snowshoeing, swimming, brisk walking on the beach, and exercise can take many forms and be practiced more or less vigorously. Aerobics, for example, is one of the sports that significantly increases the amount of oxygen consumed by the muscles and therefore requires intense work of the lungs. But more static physical activities weight lifting, balance exercises also have their uses.

Scientists have developed rigorous methods to measure the intensity of aerobic exercise. There is also an effective and less expensive way to evaluate the effort produced: the speech test. If your heart is beating a little faster, it's harder for you to breathe, but you can still talk or recite a poem while moving, your activity is still moderate. On the contrary, if you can only stammer a word or two, it means that the exercise has become intense. Finally, if you can sing, this indicates that the exercise is low intensity.

When you pick up the pace, the nervous system prepares the organs for action. Consciousness is sharper, heart rate quickens, breathing becomes faster and you sweat lightly. Blood flow decreases to organs that do not contribute to the movement, such as the digestive tract and the kidneys, while the blood vessels of the stressed muscles dilate, causing an influx of oxygen-rich blood to these tissues.

In muscle cells, oxygen migrates to the mitochondria, compartments that supply the cells with their energy. The fuel for the mitochondria is the glucose that the body produces from food. Combined with glucose, oxygen triggers very efficient combustion, producing almost 20 times more energy per molecule of glucose than in the absence of oxygen.

good for memory

First, the body burns glucose molecules stored in the liver and muscles in the form of a compound called glycogen. During physical activity, the stock of available glycogen decreases, and triglyceride molecules (they contain fatty acids) become the main source of fuel. Combustion produces certain by-products, such as lactic acid and carbon dioxide, which pass from the muscles into the blood. The increased concentration of these compounds causes biochemical reactions in the brain, lungs, and heart which facilitate their elimination.

The benefits of exercise are felt when it becomes a routine. The body adapts to the increased demands placed on it and gains endurance as the person becomes more efficient. For example, the lungs take in more oxygen as breathing becomes deeper and the heart pumps more blood with each beat. The resulting biological changes improve long-term health.

Many data confirm the effects of physical exercise on the body, whether physiological mechanisms or the activity of certain genes. Here we will focus on a few recently discovered mechanisms that help explain why physical exercise increases cognitive abilities, improves blood glucose concentration control, and strengthens the cardiovascular system.