Not surprisingly, side-lying exercises mostly work the muscles on the sides of your body. Torso toners such as side bridges and side planks work your abdominal obliques. Leg strengtheners such as lying hip abductions and adductions fire up the muscles of your outer hips and inner thighs. Side-lying lateral raises hit the delts on the sides of your shoulders.
Abdominal Obliques and Quadratus Lumborum
The internal and external abdominal oblique muscles, located on the sides of your waist, side bend and twist your trunk. The oblique muscles activate isometrically in a side plank to keep your hips from sagging toward the floor. They work dynamically to lift your hips and waist from the floor in a side bridge. The quadratus lumborum muscles in your lower back assist with side bending your trunk and are also active in side planks and bridges.
Hip Abductors
Located on the sides of your hip, your hip abductors, which include the gluteus medius and minimus as well as the tensor fasciae latae, are active in lying hip abductions. Their job is to lift your thighs to the side. The gluteus medius and mimimus run from the ilium on the side of your pelvis to the prominent knob of bone on your outer thigh bone called the greater trochanter. The tensor fasciae latae also originates on the ilium, but attaches to the iliotibial, or IT, band, a strip of tough connective tissue than runs down your outer thigh.
Hip Adductors
Lying hip adductions work your hip adductors. The adductors, located on your inner thighs, pull your thighs together. There are five hip adductors. Although lying hip adductions strengthen all five muscles, they particularly target the adductor magnus, the largest of the group, as well as the gracilis, the only adductor that crosses the knee joint. Varying the angle of your thigh during lying hip adductions by bringing it forward or backward or by changing the rotation of the thigh will target different adductor muscles.
Deltoids
Your deltoid muscles are located on the sides of your shoulders. The delts have three sections, or heads. The front, or anterior, head raises your arm forward, while the back, or posterior, head brings your arm backward. The middle, or lateral, head lifts your arm out to the side. You use the lateral head during side-lying lateral raises with a dumbbell. The lateral delt is also active in side bridges, helping to raise your body off the floor.
References
- Women's Strength Training Anatomy; Frederic Delavier
- ExRx.net: Exercise and Muscle Directory
- Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation; Donald A. Neumann
Writer Bio
Joe Miller started writing professionally in 1991. He specializes in writing about health and fitness and has written for "Fit Yoga" magazine and the New York Times City Room blog. He holds a master's degree in applied physiology from Columbia University, Teacher's College.