They may occur anywhere on the body surface as well as in internal organs, but the limbs (especially the posterior upper thigh), ventral abdomen, and thorax are the most common sites; ~ 10 % are multicentric.
Kumagai et al. (2000) found that muscle thicknesses of the top part (but not the bottom part) of the anterior (r = 0.38) and posterior (r = 0.45) upperthigh were associated with better 100m performance in a group of elite male sprinters.