Dynamic stabilizer: Biceps Brachii (short head only)
Holding a pair of dumbbells, sit on the end of a flat bench and rest the dumbbells on your knees.
Kick the dumbbells up into the air with your knees as you lie supine (on your back) on the bench.
Position the dumbbells next to the sides of your chest and hold them using a hammer grip (palms facing inward). Your elbows should be bent and tucked in to your body at a 45-degree angle.
Exhale as you press the dumbbells upward and inward in an arcing motion until your arms are fully extended over your chest.
Inhale as you reverse the motion and lower the dumbbells to the starting position or until you feel a mild stretch in your chest or shoulders.
Comments and tips
When you have finished, do not drop the dumbbells to your sides. Instead, carefully lower the dumbbells towards your thighs and allow the weight of the dumbbells to help you to sit up.
The hammer-grip dumbbell bench press places less stress on your shoulder joints than does the standard dumbbell bench press. As such, the hammer-grip dumbbell bench press is more suitable for those who suffer from shoulder pain. However, the standard dumbbell bench press, in which you of course use a pronated (overhand) grip, is arguably slightly better at activating the pectoralis major because it usually involves more internal shoulder rotation. One of the functions of the pectoralis major is to internally rotate the shoulder joint, and so the extra internal shoulder rotation that comes with the pronated grip may in some cases allow for a slightly deeper contraction.
No matter what kind of grip you use, to reduce the pressure on your shoulder joints, always keep your elbows tucked in to your torso at 45-degree angles.