The main themes presented in this volume are exercise intolerance and muscle contracture. These two topics could seem different at first sight but share common clinical features. For instance, symptoms of exercise intolerance are myalgias and cramps but metabolic contractures as well. Likewise exercise intolerance is sometimes due to dystrophinopathy, it self causing contractures. Therefore, it is justified to gather these two syn dromes in one study. Exercise intolerance and muscle contracture could seem well known, even obsolete. It is not right. A reappraisal of these has be come necessary...