Weak giants' are produced by :

In children and adolescent growth hormone hyper secretion prior to epiphyseal long bone closure causes gigantism. The muscles often appear enlarged but they have decreased force generation. So, hyperpituitarism causes giants which have weak muscles and the most common cause of hyperpituitarism is a pituitary adenoma. Myopathy of hyperpituitarism. Patients with hyperpituitarism have a mild proximal weakness with muscle atrophy. Myopathy is related to the degreed of acromegaly. Remember that all endocrinal disorders cause myopathy but none of them causes gigantism except hyperpituitarism.