The quadriceps (or quads) describe the four muscles located on the front of the thigh. They contract together to help flex (or lift up) the hip and extend (or straighten) the knee.The quads often become weak after an injury is sustained or surgery is performed on the lower leg or thigh. For this reason, it is important to learn how to strengthen this muscle group for a complete recovery. People with certain conditions often exhibit quadriceps weakness. These conditions may include: ~ Berceste