Affected young boys begin having more trouble running, climbing or walking. The examiner may observe the Gower's maneuver as as the child attempts to get up off the floor using his upper limbs to compensate for weak trunk and pelvic muscles. The calf muscles appear to be unusually enlarged (pseudohypertrophy) as muscle is replaced by fat and connective tissue. Death occurs after weakening of the respiratory muscles or from the associated cardiomyopathy. Other types of muscular dystrophy are less severe and may primarily affect a few muscles, such as facioscapulohumeral or oculopharyngeal dystriphy. Abnormalities of different muscle membrane proteins or glycoproteins characterize certain other muscular dystrophies.