The muscles and actions involved are crucial in all upward- and forward-reaching pushing and throwing actions. They're required in the sports of track and field (shot put, discus, hammer throw), basketball, gymnastics (unevens, vault and free exercise), boxing and in some martial arts.
Technique
Sit back firmly on an incline bench set at about a 30-degree angle. Place your feet flat on the floor to create a stable position. Your torso and head should be fully supported by the bench. Look directly forward at an angle perpendicular to your torso.
Hold a dumbbell in each hand with a pronated (overhand) grip with your hands just outside and in line with your shoulders. Your palms should face forward and your elbows should point downward.
Inhale and hold your breath as you press the dumbbells upward and inward. Be sure to keep your elbows out to your sides as you extend your arms over the top of your chest. Exhale toward the latter half of the lift and press the dumbbells together at the top for a second.
Inhale and hold your breath as you lower the dumbbells under control back to the starting position. Without stopping, press the weights back up and repeat for reps.
Use a moderate rate of speed, keeping the dumbbells under control at all times.
For variety and a greater range of motion in your shoulders, do alternate incline presses. Allow each shoulder to rise slightly from the bench as you raise one dumbbell at a time as high as possible.
Primary Muscles Involved
The pectoralis major, located on both sides of the sternum, is a very large muscle that makes up the bulk of the chest; the smaller pectoralis minor lies underneath. The front and middle portions of the deltoid cover the front and sides of the shoulder joint. The serratus anterior is located on the sides of the chest directly under the armpits and above the external obliques. Covering the entire back of the upper arm, the triceps has three heads, of which mainly the medial and lateral heads are active in elbow extension. The trapezius is a large diamond-shaped muscle covering the upper middle back, from the base of the head to the last thoracic vertebrae.
Muscle/Joint Actions
The muscles involved move the arms on a diagonal to the body (a combination of shoulder-joint adduction and flexion). More specifically, the arms move from a position in line with the shoulders inward and upward until they're in front of the body and above the chest. The workload falls primarily on the upper pectoralis major and middle and front deltoids. The upper and lower trapezius, together with the serratus anterior, rotate the scapula upward, while the serratus anterior and pectoralis minor abduct the scapula out to the sides to allow for the arm movement. The triceps isn't as strongly involved except near the end of the range of motion.
