How to train your hamstrings with a leg press? Well, you can’t. The hamstrings flex the knee and extend the hip, but during a leg press you’re extending at the knees. So while the hamstrings are shortened at the hips, they’re lengthened at the knees and their relative length doesn’t change, so they can’t contribute a meaningful amount of force to the movement. To target the hamstrings directly, you need to either extend the hips with a fixed knee angle (RDL, SLDL, glute raise), or flex the knee