The prison guard position involves the women bending over, while standing, in front of the man. Her arms are brought back behind the small of her back and held there by her lover. Thus, the origin of the name of the position. This position does several things to heighten arousal of both partners. Perhaps most important is the mental stimulation that it provides to both partners. The female is aroused by the prospect of being so vulnerable and trusting her mate. The male is stimulated by the amount of control he has over the situation. In addition to this mental euphoria there exists excellent physical stimulation.
When the female bends over at the waist she is pushing her vagina into the male allowing him to get better penetration. The female can also control the level of penetration by holding her legs close together or raising her waist up and down to control access to her lover. Lowering to the floor will have the effect of making it harder for the male to penetrate, but will allow the female to stay in control once again. This position can also be modified to allow both partners to relax their muscles. An ottoman could be provided to allow the female to rest on her knees and experience different angles of penetration for a more comprehensive experience. If the male carefully lowers himself to the ground, he can give the female an increased sense of control, and both people can rest their legs before rising back up into the prison guard position.