Good exercises to tighten sagging skin include air biking, bicep curls, cardio workouts, core workouts and crunches. Other skin-tightening exercises include leg raisers, lunges, pelvic thrusts, planks and squats. Skin can loosen due to weight loss, pregnancy and aging and typically becomes loose around the stomach, arms and upper legs.
To perform the skin-tightening air bike exercise, lie down on the floor, put your hands behind your head, and pull up your knees. Pull your right elbow to your left knee until they are almost touching, and do the same thing for the opposite elbow and knee. Repeat the exercise for 30 seconds. Bicep curls are effective at tightening loose skin under the arms. For cardio workouts, alternate exercises at different speeds, and focus on as many muscle groups as possible. During crunches, make sure to keep your back straight and your chin level, and raise your torso to your knees against resistance.
To see improvement in three months, do 30 double and single leg raisers twice every day. Doing lunges is essential to tighten the skin on your upper thighs. To do pelvic thrusts, lie down on your back, raise your legs at 90 degrees, and slowly lift your pelvis off the floor and upward. Slowly lower your pelvis back down, and repeat. For planks, get down on the floor as if to do push ups. Keep your arms, legs and back straight, and hold for as long as possible.