[Physical activity and disease]

The sedentarism is a frecuent situation in our modern society, and represents a risk factor for a vast array of pathology. The physical activity produces several positive effects, which decreases the general morbi-mortality of the population. There is made a commentary about some definitions: Exercise, activity and physical form, aerobic and anaerobic work, muscle exercise. Their pathophysiology and their health benefits. We described the measurement procedures: calorimetry, oxigen consum, accelerometers, pulsometers and cuestionnaries. There is finally done a review upon practical norms.