Adjust the seat and footplate of the sled machine to a comfortable position. Sit on the sled machine with your back against the backrest and your feet shoulder-width apart on the footplate. Grip the handles on the sides of the seat for stability. Push the footplate away from your body by extending your legs, keeping your heels on the footplate. Continue pushing until your legs are almost fully extended, but without locking your knees. Pause for a moment at the top of the movement, then slowly lower the footplate back towards your body by bending your knees. Repeat for the desired number of repetitions.
GIF