Stand with your feet at around shoulder-width apart or even narrower. The feet should generally point forward in line with knees. Narrow stance squats target primarily the quadriceps, glutes, and adductors.
Your jumps should be roughly 1-2 inches off the ground. Keep your toes pointed down slightly on every jump and make sure there is always a slight bend in your knees and that you are landing softly on the balls of your feet every jump.
Stand upright with your legs together, arms at your sides. Bend your knees slightly, and jump into the air. As you jump, spread your legs to be about shoulder-width apart. Stretch your arms out and over your head. Jump back to starting position.
Get into a plank position, making sure to distribute your weight evenly between your hands and your toes. Check your form—your hands should be about shoulder-width apart, back flat, abs engaged, and head in alignment. Pull your right knee into your chest as far as you can.
Switch legs, pulling on...