The straight leg raises can be a simple way to target the quad muscles properly. Start by lying on the floor on the back. Bend the uninvolved leg’s knee to a 90-degree angle while keeping the foot flat on the ground. Make sure the other leg is straight with toes pointed to the ceiling. Contract the muscles of your front thigh to lift up the involved leg slowly. Stay in this position for at least 5 seconds before lowering the leg. Do 15 reps in total.