A lateral raise involves lifting a resistance by bringing your arms out to your sides while holding a weight in each hand with your hands facing down or facing the front. This exercise trains different muscle groups that both stabilize your body to maintain your posture and balance and to lift the resistance.
The deltoids are the large, outer shoulder muscles that cover the front and back of your shoulders. They lift your arms up to your sides at about 90 to 110 degrees when your shoulders are internally rotated. They also work eccentrically to lower your arms back down to your sides.
The rotator cuffs are made up of four muscles that work together to maintain shoulder joint stability, externally and internally rotate your arms, and move your arms away and toward your body. These muscles include the teres minor, subscapularis, supraspinatus and infraspinatus. Lateral raises increases stabilization strength in your rotator cuffs. Be aware that these muscles can get seriously injured if you perform this exercise with too much weight or with improper control and form.
Your core is made up of the inner unit and outer unit, which work together to stabilize your spine and hip when you move, according to the National Academy of Sports Medicine. The inner unit, including the transversus abdominis, internal obliques and multifidi, are close to your bones and organs, while the outer unit, including the rectus abdominis, external obliques and external spinae, are near the surface of your body. When you perform a lateral raise, both units work together to stabilize your body to prevent you from moving as you move your arms. Otherwise, your body compensates the exercise by hunching your shoulders or arching your lower back.
Arms and Hands
Lateral raises also improves grip strength, building muscles in your forearms -- including the arm flexors and extensors -- and in your hands, such as the intrinsic and extrinsic muscles that control flexion and extension of your thumbs and fingers. After each set of lateral raises, move your thumbs and fingers by opening your hands wide and closing them repetitively in a controlled manner.
This large triangular muscle in the surface of your upper back assists your deltoids and rotator cuffs to lift during the lateral raises. It also pulls your shoulder blades back to maintain your posture and avoid hunching forward.