Leg extensions are exercises usually done with a lever machine. You sit on a padded seat and raise a padded bar with your legs. The exercise works mainly the quadriceps muscles of the front of the thigh—the rectus femoris and the vastus muscles.

Adjust the height of your seat so your legs are bent at 90 degrees with your lower shins behind the pad. Sit back in the chair and hold on to the handles by your sides. Retract your head. Pull your shoulder blades back and down. Draw your navel towards your spine to engage your abs. Try not to arch your back to maintain a neutral spine.

Take a seat at the leg extension machine with the pad at the top of your lower legs, at the ankles. Select a heavy weight, something you are comfortable doing several sets with Rest your hands at your sides, holding the support bars Lift the weight using your quad muscles until your legs are almost straight out in front