Before doing the dumbbell scaption, warm up your shoulders by doing three sets of arm circles for 45 to 60 seconds per set. Once you do this, grip a dumbbell in each hand with an underhand grip and stand or sit with your feet shoulder-width apart. Keep your torso upright and position the dumbbells by your sides, with your arms slightly bent and palms facing forward. Raise your arms 45 degrees between your forward and side planes. Once your arms are parallel to the ground, lower them down towards your sides.
The primary muscles worked during dumbbell scaption are the deltoids. In particular, the anterior and lateral deltoids. These are your front and side shoulder muscles. Your anterior deltoids are made up of two segments, or parts, while your lateral deltoids are made up of only a single segment.
Supraspinatus and Other Rotator Cuff Muscles
The supraspinatus is small muscle located at the top of your scapulae, or shoulder blades. This muscle is actually one of four rotator cuff muscles, which are all important in maintaining shoulder stability. During dumbbell scaption, the supraspinatus is largely responsible for initiation of the motion and it remains the main mover until about 30 degrees of scaption. The other rotator cuff muscles, which are the subscapularis, infraspinatus and teres minor, all play a role in maintaining the stability of your shoulder throughout the range of motion.
Clavicular Pectoralis Major
Another muscle involved during dumbbell scaption is the clavicular segment of the pectoralis major. This muscle is also known as the upper chest and is located next to the anterior deltoid, extending toward the middle of your upper-chest region. However, the anterior deltoid is much more involved during dumbbell scaption. The clavicular pec major only acts as an assisting mover.