The windmill earns high marks as a core-muscle builder. It promotes strength in the abs, hips and back, which can lead to improvements in posture, balance, stability and overall function. Featuring an open stance, outward thrust of the hip and forward hinge of the torso, the exercise also develops hamstring flexibility and hip-joint range of motion. Adding free weights to the basic variation boosts arm and shoulder strength and increases the overall challenge.
Warm up with some form of cardiovascular activity. Jog in place, jump rope or do jumping jacks for three to five minutes to raise your core body temperature and increase circulation. When you break a light sweat, do some dynamic stretches -- involving continuous, smooth and repetitive movement -- to further prepare your muscles and joints for activity. Use a combination of arm circles, torso twists and light leg swings to the front to warm your shoulder, abdominal, back, hip and hamstring muscles.
Do a basic windmill without resistance to master the movement pattern. Stand with your feet more than hip-width apart and your toes facing forward. Extend your right arm overhead and let your left arm relax at your side. Angle your left foot outward, drive your weight into your right heel and begin shifting your right hip outward to the right. Turn your head and lock your eyes on your right hand. Continue thrusting your hip outward, bend your left knee slightly and let your left hand track along your left leg until your fingertips touch the floor. Pause briefly and then return your torso to an upright position, leaving your right arm extended upward. That's one rep. Repeat the move five to 10 times, keeping your right arm extended overhead at all times. Switch sides and repeat.
Add a medicine ball, kettlebell or dumbbell. Begin with the weight on the floor slightly in front of you. Engage your abs to support your lower back, bend your knees and hinge forward from your hips slightly. If you're working with a medicine ball, grasp it firmly with both hands. If you're working with a kettlebell or dumbbell, grasp it with your right hand. Keeping a straight spine, return your back to an upright position while drawing the weight toward your right shoulder. Extend your right elbow, pressing the weight overhead. If you're using a medicine ball, balance it on the palm of your hand. If you're using a kettlebell or dumbbell, your right palm should face away from you and your wrist should be straight. Continue as you would with the basic windmill, keeping your right arm locked out and your eyes focused on the weight to maintain control.
Vary your use of free weights to decrease or increase difficulty. If working with a free weight overhead is too strenuous, grasp a kettlebell or dumbbell with your lower hand instead. Keep your eye on your upper hand and jut your hip outward as you would with the basic exercise, lowering the weight until it touches the floor lightly. As you return your torso to an upright position, slowly raise the weight off the floor. Repeat five to 10 times and switch sides. For greater challenge and intensity, hold a kettlebell or dumbbell in each hand.
Round off the exercise with light stretching to prevent soreness and maintain flexibility. Include stretches for the main muscle groups you worked, including your abs, shoulders, triceps, back and glutes.