The leg press is an exercise that utilizes a weight machine to help build the muscles in the upper leg. There are a few different types of leg presses, but because they are relatively similar and contain little variation, only one type needs to be done to accomplish the requisite range of movements of the exercise.
Horizontal Leg Press
The horizontal leg press is also sometimes known as the seated leg press because it occurs upright in a seated position. The feet are pressed against a plate which is attached to a weight stack through a long steel cable. In a neutral position you should keep the knees bent. When you straighten the legs, you press against the plate and pull the weights.
Vertical Leg Press
The vertical leg press is very similar to the horizontal leg press, except your back should sit against the floor with your legs positioned straight up into the air. The body is bent midsection at a 90 degree angle, and your legs are pressed up against a plate that faces downward. The weight is on top. Straightening the knees presses the weight upward.
45 Degree Leg Press
Another variation of the leg press is done at a 45 degree angle. The person is seated into an incline sled and presses outward with the legs. This is also sometimes known as a vertical leg press, although the legs are positioned halfway between the vertical and horizontal presses.
Both workouts generally require the same range of motions. The main target muscles are the quadriceps in the thighs and the gluteus maximus in the buttocks. The hamstrings, which are also in the thigh, are part of the secondary muscle group targeted by the leg press. Varying the angle of the legs changes the emphasis placed upon the muscles.
The risk of injury compared to other leg exercises is significantly reduced in the 45 degree and vertical leg press, where the burden is assumed by the legs and the back is in a stabilizing position. In the vertical leg press the body movement isn't actually working directly against gravity, despite the upward mobility of the weights, so there isn't an additional strenuous pressure upon the legs. The horizontal leg press also limits injuries, though not quite as much.