Dynamic stabilizer: Biceps Brachii (short head only)
Sit on a stability ball with a dumbbell in one hand.
Roll your buttock downwards until your back is resting against the ball, with your torso forming a 45-degree angle with the floor.
Spread your feet and position the dumbbell to your chest with your elbow bent and slightly tucked into your torso.
Exhale as you press the dumbbell upward and inward until your arm is almost fully extended.
Hold for a count of two.
Inhale as you lower the dumbbell back to the starting position.
Repeat for the desired number of repetitions.
Repeat with the opposite arm.
Comments and tips
The incline one-arm dumbbell press on stability ball activates even more stabilizer muscles compared to the incline one-arm dumbbell bench press. This is because the stability ball is more unstable than an inclined bench.
Slightly tuck in your elbow to reduce pressure on your shoulder joint.
Keep your balance by spreading your feet and planting them on the floor.
It is important that your torso forms a 45-degree angle with the floor because the clavicular head of the pectoralis major is most active at around this angle.