A leg press is an isolation exercise that targets muscle groups throughout your lower body, including your quadriceps, hamstrings, and glutes. Practice leg presses by sitting against the backrest of a leg press machine. Place your feet against the footplate with your knees bent at a 90-degree angle. Slowly push against the footplate to move a pulley attached to weight plates. Return the footplate to its original position and repeat for the desired amount of repetitions.