This is called dormant pruning. The least favorable time to prune is late summer when new succulent growth would not be sufficiently hardened-off before frost. Any obstacle placed in such a way as to train a limb into a more horizontal position is called a spreader. Horizontally growing limbs develop wide crotch angles that are strongly attached to the tree. Horizontal limbs are less vigorous and are apt to fruit more productively than the vegetatively vigorous vertical shoots.
Vertical shoots are apt to maintain vegetative growth at the expense of fruit production.
Horizontal branches will be less vigorous and bear fruit.