The corpora cavernosa are a pair of chambers on either side of the penis. If you view the penis from above, imagining a line dividing it down the center, the corpora cavernosa chambers fall to the left and right of the line. As you become aroused, both sides fill with blood, which produces an erection.
Corpora Cavernosa Enlargement Theory
The theory behind penis enlargement is that if it is possible to expand the corpora cavernosa, you will naturally attain a larger erection. This is purportedly accomplished through the repeated forcing of blood through the tissues of the penis. Over time, this supposedly has the net result of triggering tissue expansion, resulting in a larger overall member.
Corpora Cavernosa Exercise
According to Thunder's Place Penis Enlargement Forums, the main exercise intended to expand the corpora cavernosa is the jelq. Jelqing is accomplished by attaining a partial erection to bring some blood into the penis. Grip the penis firmly around the base and pull forward, forcing blood through the corpora cavernosa towards the head of the penis. This should be done slowly, taking three to four seconds to complete a single "jelq."
To begin, perform jelqing for a period of 10 minutes. Aim to train every other day to give your body time to rest and rebuild the damaged tissue. When training, aim to strike the right balance between intensity and safety, aiming to exercise hard enough to produce results, but not so hard that you inadvertently injure yourself. There is no hard and fast rule to know how much is too much--just use common sense to prevail.
Note that there is no scientific proof that penis enlargement exercises will work to increase the size of the corpora cavernosa. In fact, some individuals even warn that practice of these exercises could result in permanent damage. The doctors at the Mayo Clinic caution that performance of penis-enlarging exercises can result in the formation of scar tissue within the penis or even permanent deformation of your genitals.