This exercise targets the triceps brachii to strengthen the upper arm. Extensions with one arm are auxiliary utility exercises that place high relative intensity on the head of the triceps brachii muscle. The extension involves movement by means of concentric muscle contractions that pull the limb away from the center of the body. It involves movement by a single joint, which is effective at targeting the muscle through isolated mechanics. The extension stabilizers include the latissimus dorsi, the flexor carpi ulnaris, the extensor carpi ulnaris, the teres major, the sternal pectoralis major, the clavicular pectoralis major and the posterior and anterior deltoids. Begin with 2-3 sets consisting of 8-10 repetitions and gradually lengthen the routine. Eventually, the routine should consist of 4-5 sets of 10-15 repetitions. Pain caused by excessive tension is common in one-armed exercises, but extending the arms and pulling weights toward the upper chest between repetitions can provide relief.
How to perform the one arm extension
Stand with your feet approximately shoulder width apart, holding a light dumbbell in your left hand, press the dumbbell overhead so your arm is straight, without moving your upper arm, bend your elbow, and lower the dumbbell behind your head as far as possible, extend the dumbbell back overhead until your arm is straight.