The leg press is a resistance machine that provides numerous benefits, but the exercises done on these machines can become dangerous if you don't maintain stability. The area most compromised when the leg press is performed in an unsafe manner is the spinal column. Several factors can cause spine or back pain during the leg press.
Seat Position
One cause of spinal injuries during a leg press is improper seat placement on the machine. Seat positioning is more important on leg press machines than on some other types of resistance machines, because your lower spine becomes compromised when the seat on a leg press is too far forward. If resistance pushes your hips past 90 degrees, your spinal column becomes heavily strained. A 90-degree angle at the hip gives your legs an appearance of a right angle.
Excessive Resistance
Another cause of back injuries on the leg press is excessive resistance. An appropriate resistance allows you to be challenged yet also move the weight in a controlled fashion. Resistance that is too heavy for you prevents control and creates joint imbalances. Common joint abnormalities are overarching of the lower spine, knee hyperextension, hip elevation and neck strain. All of these joint deviations directly affect the spinal column.
Excessive Movement Speed
Back injuries can also be caused by moving the resistance too fast. Excessive speed can occur when the weight is too heavy for you; your body responds to an overwhelming resistance by accelerating the movement speed. Rapid muscle movements place an exorbitant amount of stress on stability joints. The prime stability joints for the leg press are the knees, hips and lower spine.
Proper Orthopedic Position
A leg press is one of the more effective lower-body strengthening exercises, but proper orthopedic, or joint, positioning is vital. Correct seat positioning allows your entire body to be completely stabilized. Full joint stabilization allows the quadriceps, gluteals and hamstrings to be completely engaged through every resisted motion. The quadriceps, gluteals and hamstrings are the target muscles on the leg press.
The seat/back pad of a leg press is situated so that the legs are just shy of a right angle. You sit with your hips and spinal column pressed against the back pad of the machine. Your head and neck are both straight and relaxed. Let your arms hang at your sides. Your feet are hip-width apart and are flat on the platform. Your knees remain aligned with the tips of your shoes throughout the exercise.
Alternative Exercises
Alternative exercises exist for every resistance machine, so you aren't excluded from muscle movements just because one machine isn't recommended for you. A ball squat recruits the same target muscles as the leg press. It also moves through similar joint actions. The major differences between leg presses and ball squats are body position and type of resistance. Ball squats are executed while you're standing, with your body weight acting as the main source of resistance. You can progress this exercise by holding external resistance, such as dumbbells or a medicine ball.
References
- "Techniques in Musculoskeletal Rehabilitation"; William E. Prentice , Michael L. Voight;; 2001
- "Spinal Rehabilitation"; David E. Stude; 1999
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