The most obvious effect of running is that it burns calories and raises the metabolic rate—the rate at which the body uses energy. This can help control weight. Running also builds and tones the muscles, particularly in the lower half of the body. Being toned and fit makes it easier to do other physical
activities. But running, and any other form of regular exercise, also affects other systems of the body.
Running is a form of aerobic exercise—the heart rate increases during this activity. When the heart rate is raised, the whole cardiovascular system (the heart and blood vessels) gets a workout. Regular workouts make the cardiovascular system run more efficiently. But what does this mean? The heart is a muscle, so when the heart rate gets raised during exercise, the heart gets exercise. Regular exercise makes the heart, and the other parts of the cardiovascular system, stronger and helps it run more efficiently. The heart pumps more blood with each beat. This in turn helps the blood vessels retain elasticity. The increased volume of blood also carries more oxygen from the lungs to the other parts of the body. The lungs get a workout as well, because of the increased breathing rate during a run.
But why are these effects important? Weight control plays a leading role in preventing type 2 diabetes, a disease in which the sugars in food are not properly metabolized. This disease is growing dramatically around the world, particularly in countries undergoing rapid industrialization. People with diabetes are more likely to develop kidney disease, cardiovascular disease, blindness, gangrene, and other illnesses.
Regular exercise reduces blood pressure, thereby helping to control hypertension (high blood pressure). Exercise also raises the good cholesterol (high-density lipoproteins, or HDL) and lowers the bad cholesterol (low-density lipoproteins, or LDL), the kind of cholesterol that builds up in the arteries. All of this helps prevent heart attacks and strokes, as well as other cardiovascular diseases.
Another advantage of running is that it is a weight-bearing exercise. Exercise in which muscles pull on bones helps stimulate bone building. This makes them stronger and healthier.
If any aerobic, weight-bearing exercise gives the body a good overall workout, why choose running? The answer is the simplicity of the activity. Running can be done outside on roads or indoors on a track or treadmill. It requires very little equipment beyond good running shoes, and it can be done in warm or cold weather.