If you want to tone, strengthen and firm you upper arm and forearm, you still have some time before summer ends! The alternate dumbbell curl is a premier arm exercise because it activates all of the muscle fibers, including the important supination properties of the arm. The end result is that your upper arm will be strengthened, toned and firmed.1
The biceps brachii muscle of the front (anterior) part of your upper arm has two heads.2 The short head of the biceps attaches to the front part of the scapula bone or “shoulder blade,” and it runs along the medial (inner) part of the humerus bone of the arm. The long head of the biceps muscle attaches to the scapula bone just above the shoulder joint, and it runs along the lateral part of the humerus to the elbow. The short and long heads of the biceps brachii muscle come together to make the bicipital tendon, which crosses the anterior part of the elbow and it inserts into the radius bone just beyond the elbow joint. The biceps heads flex the elbow at the forearm2 (bring the hand toward the shoulder). The attachment of the bicipital tendon to the radius bone of the forearm permits a pivoting of the radius bone, which supinates the hand (turn the palm towards the ceiling). The supination that is possible with standing alternate dumbbell curls makes it superior to machine curls.
The brachialis muscle is an elbow flexor muscle that is deeper than the biceps brachii muscle, but it is just as important. It attaches along the anterior side of the humerus bone and it crosses the elbow joint anteriorly to connect to the ulna bone of the forearm near the elbow joint.2 The ulna does not pivot, so the brachialis muscle is an effective flexor, whether the hand is supinated or pronated. The brachioradialis is a forearm muscle, but because it crosses the elbow joint, it can be very active during alternate dumbbell curls. It begins on the lateral side of the humerus bone above the elbow joint and it extends to the radius bone of the forearm near the wrist joint. It does not cross the wrist and therefore it only flexes the elbow joint.2
Standing Alternate Dumbbell Curls
1. There is no need to try to lift heavy weights here. Rather, pick up two medium-weight dumbbells. If possible, stand in front of a mirror (to watch your exercise form). Place your feet about shoulder-width apart. Turn your hands so that the palms are semi-pronated (i.e., with palms facing the side of the thighs).
2. Flex (bend) the elbow of one arm so that the dumbbell moves closer to your face. After the dumbbell has moved upward past your hip, begin turning the palm of the hand toward the ceiling (supination). The upper arm should remain perpendicular to the floor as you are curling the weight upward or you will reduce the effect on the long head of the biceps.3 Try to keep the arm in close to the side of the ribs.
3. Continue to supinate the hand further as you curl the weight upward toward your face. Do not let your elbow travel forward more than a few inches at the top.
5. Slowly lower the weight toward the floor while at the same time you are reversing the hand position back to its semi-pronated starting position. Be careful that you do not hit your thigh with the dumbbell on the descent of the weight.
6. Repeat the same sequence with the other arm. Alternate the contractions between arms until your set is completed. Replace the weight on the floor after the set is finished.
The semi-pronated starting hand position maximally activates the brachialis and the brachioradialis muscles at the start of the movement. However, when the hand becomes supinated, the biceps make a much greater contribution to the exercise. This is the perfect combination for activating all of the upper arm muscles. You should try to do the exercise with a controlled velocity, 4 but without “cheating” by swinging the hips to help thrust the weights upward. If you cannot maintain good form during the exercise, you should choose a lighter dumbbell.
Start with only one set for the first week – otherwise your arms may become sore afterward.5 However, work up to 3-4 sets of 10-12 repetitions5 over the following several weeks.
Alternate dumbbell curls are especially effective if you want sexy and firm arms and forearms.6 The added benefit is that dumbbell curls have both a strength and an aerobic component and this provides you the ultimate arm shape-training experience.1,7
1. Coke LA, Staffileno BA, Braun LT et al: Upper-body progressive resistance training improves strength and household physical activity performance in women attending cardiac rehabilitation. J Cardiopulm Rehabil Prev 2008;28:238-245.
2. Moore K.L, and A.F. Dalley. Clinical Oriented Anatomy 4th Lippinot Williams Philadelphia, 1999; pp. 720-756
3. Moon J, Shin I, Kang M et al: The Effect of Shoulder Flexion Angles on the Recruitment of Upper-extremity Muscles during Isometric Contraction. J Phys Ther Sci 2013;25:1299-1301.
4. Ingebrigtsen J, Holtermann A, Roeleveld K: Effects of load and contraction velocity during three-week biceps curls training on isometric and isokinetic performance. J Strength Cond Res 2009;23:1670-1676.
5. Radaelli R, Bottaro M, Wilhelm EN et al: Time course of strength and echo intensity recovery after resistance exercise in women. J Strength Cond Res 2012;26:2577-2584.
6. Matta T, Simao R, de Salles BF et al: Strength training’s chronic effects on muscle architecture parameters of different arm sites. J Strength Cond Res 2011;25:1711-1717.
7. Dunsky A, Ayalon M, Netz Y: Arm-curl field test for older women: is it a measure of arm strength? J Strength Cond Res 2011;25:193-197.