This Is MS Multiple Sclerosis Community: Knowledge & Support

What does exercise do to your body? It may seem as if science, medicine and common sense answered that question long ago. But in fact, the precise mechanisms by which exercise alters your body — at a deep, molecular level — remain poorly understood. A number of analyses of the effect that exercise has on heart disease, for instance, have concluded that working out lessens a person’s chances of developing heart problems far more than scientists can account for. They understand the physiological reasons for about 60 percent of the reduced risk. The rest is a mysterious if welcome bonus.

But a new study that gauged the metabolic effects of exercise may significantly advance our understanding of what’s going on inside a body in motion. During the experiment, scientists actually saw how much being fit changes your ability to incinerate fat, moderate blood sugar and otherwise function well. They also uncovered proof, at once inspiring and cautionary, of just how complicated and pervasive exercise’s consequences are.