The leg press is a compound exercise that targets the lower body. The exercise engages the quads, the hamstrings and the calves, as well as the gluteals and lower-back muscles. Even though the leg press is a compound exercise, the motion occurs in a simple two-phase movement that you can perform on one of two styles of machine. Both phases of the press provide a thorough lower-body exercise, but each must be performed safely and smoothly to achieve total effectiveness.
The eccentric phase is the first part of the leg press, where your legs are fully compressed and bent at the knees and you press the pedal platform away from you. The eccentric phase continues until your legs are fully extended and your knees are locked. The quads provide most of the push for the initial lift during this phase but the gluteals and calves also contribute to the eccentric aspect of the leg press.
The concentric phase begins when you lower the pedal platform back to starting position, controlling the weight as your legs compress. This phase of the lift engages the hamstrings primarily to control the weight as your legs compress. You may be tempted to let gravity help you complete the concentric phase, but this robs you of achieving complete gains from the leg press. The concentric phase is where you need to prepare to engage the safety mechanism on the machine if you begin to lose control of the weight.
While the leg press has only two distinct phases, the type of machine you use determines where in the exercise you begin the press. The leg press on the lateral-seated machine begins the press with the concentric phase, goes through the eccentric phase, then returns to the beginning. The sled leg-press machine seats you at a 45-degree angle to the floor and, in most cases, begins with the pedal platform at the top of the motion, requiring you to lower it until your legs are completely compressed then return to start. This is your first rep.
Most leg-press racks provide a safety mechanism that is activated by turning a handle up or down to prevent the weight from traveling down too far during the concentric phase. Make sure you’re completely familiar with the mechanism prior to your leg-press reps. Schedule adequate recovery time following your leg-press workouts to let your muscles fully regenerate. It’s easy to overtrain your leg muscles since they can handle a comparatively large amount of weight.
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