5. IN-AND-OUT SQUATS
WHY IT WORKS: In-and-out squats will put you on the fast track to leaner, more toned legs. The exercise trains your thigh muscles to isometrically stabilize your knees with a dynamic side-to-side movement with your feet. It also recruits your body’s biggest and strongest muscles, which causes a metabolic disturbance significant enough that you’ll be burning calories even after you stop doing it. These squats are also a lower-impact alternative to traditional up-and-down squat jumps for those individuals who suffer from knee pain.