If you are looking for an alternative to the barbell squat, then one legged squats is the right alternative thigh exercise. It helps in strengthening the muscles of the legs. Concentration and balance are the two other benefits of this exercise. Since only one leg is used to do this exercise, it helps in developing balance. It works the gluteal muscles, hamstrings, quadriceps as well as the core muscles. It can also be used as an alternative to hip extension and knee extension.