- For the PUA technique, see Frame (PUA)
Frame is dictated by bone circumference, wrist size, hand width and length, wingspan, ankle thickness, foot width, clavicle length, ribcage circumference and hip width (which is also related to pelvis bone size)
It is said that breathing squats and pullovers could expand ribcage. Wolff's law states that bones remodel over time under pressure. Breathing squats are suggested to expand the ribcage as the lungs exert pressure. This was a technique practiced by many 'old school' bodybuilders before this idea fell out of fashion.
A large ribcage could house larger lungs, which helps to deliver oxygen to the muscles. The clavicles widen in response to growth of the ribcage.
Females, in contrast, have less muscle and so they do not require large lungs support their muscles. Hence they have smaller ribcages.