The Leg Press

Execution:

• Assume a seated position on a leg press machine angled at approximately a 45º angle.
• Place your feet against the resistance platform with your hips and spine against the back support.
• Your feet should be shoulder width apart and placed in the middle of the resistance platform. Pressure should be felt on the entire soles of both feet.
• Release the locking lever located on the sides of the seat and then straighten the legs.
• The legs should be fully extended but not locked and the trunk should be held firmly against the back support. This is the starting position.
• Inhale slightly more than usual and hold your breath as you bend (flex) the legs to lower the platform. Lower at a slow to moderate speed.
• Bend your legs until there is an 80-90? angle in the knees (measured from the back of the shin to the back of the thigh).
• At this point, keep holding your breath and straighten the legs to press the resistance platform back to the starting position.
• Exhale as you pass the most difficult part of the upward pressing action.
• Fully extend the legs but do not lock out the knees and then pause momentarily in the end position.
• Inhale and bend the knees to allow the resistance platform to move downward until you once again have an 80-90? angle in the knee joints. Then push back and fully extend the legs. Repeat for the necessary number of repetitions.

Performance:

• To help prevent back injury, be sure that the knees do not get close to the chest during the lowering phase. The closer the knees get to the chest, the greater is the rounding in the lower back which puts pressure on the lumbar intravertebral discs and can cause injury. On most machines, the 90? knee joint angle is the optimal angle for back and knee safety.
• Breath holding plays an important role not only in exercise safety but in effective execution. When you hold your breath, you generate more force and stabilize the trunk to allow for more effective leg actions.
• Exhalation on the return or after passing the sticking point relieves the built up intra-abdominal and thoracic pressure and helps to relax the muscles somewhat in preparation for the next repetition.
• To stress more of the gluteus maximus and hamstrings, place the feet higher on the resistance platform. If you place the feet low, you will stress the quadriceps more. However, each of these foot placements depends upon your hip joint flexibility and how well you can handle the stress not only to the knees but also to the lower back.
• Be sure that you do not lock out the knees at the end of the movement, especially if you naturally have several degrees of hyperextension in the locked position. This can lead to excessive hyperextension, which can severely injure the knees.
• Leg press machines commonly cause low back injury because of the rounding of the back when the knees are close to the chest. To prevent injury, be sure that you do not exceed the recommended angles (approximately 80-90? in the knee joint), and that you have adequate flexibility in the hip joint (hamstring and gluteus maximus).
• In comparison to the free weight squat, the leg press allows you to use much more weight; in some cases, well over twice the amount used in the regular squat. The extra weight is needed for greater intensity but you should always use caution to prevent injury.

Primary Muscles Involved:

The primary muscles of the hip joint are the gluteus maximus and hamstrings. The gluteus maximus is one of the largest muscles in the body and is located at the back of the hip (the muscle you sit on). The hamstrings are composed of three muscles: the biceps femoris, semitendinosus and semimembranosus. The biceps femoris is the largest of the three and is typically the muscle that is well defined on the inner back of the thigh. The primary muscle of the knee joint is the quadriceps femoris, which consists of four major muscles: the vastus lateralis; vastus medialis; vastus intermedius and the rectus femoris. These muscles run almost the entire length of the thigh and converge into the quadriceps femoris tendon that attaches to the patella (kneecap). The vastus lateralis, a large muscle located half-way down the outer side of the thigh and the vastus medialis, located on the inner side of the thigh and somewhat lower than the lateralis, are known as the teardrop muscles. The vastus intermedius lies between the vastus medialis and lateralis and beneath the rectus femoris, which is a large muscle that crosses both the hip joint and the knee joint. It is positioned straight down the front of the thigh.

Muscle and Joint Actions:

The major action in the knee joint is extension in which the back of the thigh and back of the shin move away from each other in a leg straightening action. The quadriceps is the main muscle involved in this movement. The major action in the hip joint is extension in which the thighs move away from the trunk toward alignment with the upper body. On a 45?-angle leg press machine, they move to a position perpendicular to the trunk. In hip extension, the gluteus maximus is involved early and the hamstrings do most of the later work. The hamstrings are two-jointed muscles with actions at the knee and hip joints. The knee straightening action makes the hamstrings more taut to make the contraction even stronger at the hip joint as the legs are straightened.

Sports Uses:

Without hip and knee joint extension, lifting heavy weights off the floor would be impossible. These dual actions allow you to move the upper body in a straight pathway upward which is critical in the deadlift and squat in powerlifting and the snatch and clean and jerk in weightlifting. Women need this exercise to develop and define mainly the anterior thigh, especially the middle portion, and the middle to upper portion of the posterior thigh and buttocks. Knee and hip joint extension and the muscles involved are extremely important in a multitude of sports. These actions are used in all forms of jumping, running, lifting and pushing and are especially important in sports such as track and field (throwing, jumping and running events), basketball and volleyball (jumping), and snow and water skiing. The leg press is also used to enhance knee extension as for example, in kicking (soccer, karate) and knee and/or hip extension is very important in some of the swimming strokes, especially in the free-style, butterfly and breast-stroke.