In addition, since isometric exercises are done in a static position, they won't help improve speed or athletic performance. They can be useful, however, in enhancing stabilization â maintaining the position of the affected area â since muscles often contract isometrically to aid in stabilization.
Etiology. Most (85-95%) substernal thyroid masses represent benign goiter. Historically, goiters have generally occurred because of iodine deficiency, although this is now observed primarily in developing nations.
Hyperthyroidism may be observed in cervical or substernal goiters. Thyrotoxicity in goiters may be due to an autonomously functioning nodule or may be precipitated by ingestion of iodides found in certain expectorants or in radiographic contrast media.