The setup on the leg press can be confusing for some people, especially when you first get into the gym, but just by adjusting the feet you can target different muscle groups more and enhance the exercise for dealing with knee, back and hip pain.
For the average person, setting up the leg press with a shoulder stance is recommended with the toes pointed slightly outward. Notice, you should always keep the knees tracking with the toes on this exercise, as this joint doesn't handle extreme rotation well.
For a bit more glute and hamstring activation put the feet up higher and wider on the foot plate, with the toes rotated out a bit more (about 30degrees should suffice). This stance is recommended for those with knee pain or low back pain since you can flair the knees out wider and mimics more of a squatting stance. Also keep in mind to keep the back at a slight arch and bracing the core is always a necessary evil to avoid excessive back stress while leg pressing.
For more quad activation place the feet lower on the foot plate and bring the knees closer together. Be mindful that this will place more stress on the lower back as well the deeper you go. This foot placement is not recommended for those with knee pain, as it will shift your emphasis more onto the front of the foot thus placing more stress on the knee joint.
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