leg extension modifications.
The exercise works mainly the quadriceps muscles of the front of the thigh—the rectus femoris and the vastus muscles. You can use this exercise to build lower body strength and muscle definition as part of a strength training workout.
basic how to.
Set up the leg extension machine so the pad is at the top of your lower legs at the ankles. Your knees are at 90 degrees. Select a weight that will give you a moderate load for 10 to 12 repetitions.