Firm and sleek upper arms can provide the perfect finishing touch to the hours you spend working toward perfecting your fit physique. Although your arms can be covered up by sweat shirts during the winter, they will be on display in just about everything you wear during the summer and into the fall. Even though we are at the end summer, it is not too late to add a bit more firmness and shape before you are once again forced to wrap up your upper body for the cooler months. Moreover, travels might take you to warmer climates, so there is no real reason not to have your arms as tight and toned as you can.
Firm upper arms will require you to invest in some direct work, and seated machine preacher curls provide an effective tool to shape the elbow flexor muscles of your anterior arm without exhausting other muscles. Do not worry about bulking up your arms with this exercise, since you will not need heavy weights to stimulate your muscle fibers and work their magic on your upper arms.
Arm Structure
The anterior compartment of the arm contains the biceps and brachialis muscles. These muscles function primarily at the elbow joint, although parts of these muscles also function at the shoulder joint. The biceps brachii is a two-headed muscle. The long head of the biceps brachii has its upper attachment on a bump over the shoulder joint called the glenoid tubercle. It sits on the lateral (outer) part of the arm, and its fibers intertwine with the short head of the biceps as it approaches the elbow. Because the long head of the biceps brachii crosses the shoulder, it becomes involved during shoulder flexion (i.e., bringing the arm forward). This anatomical positioning also means that the arms and elbows need to be back to stretch the long head, to maximize the stretch and activation of this muscle belly during elbow flexion.
The short head of the biceps is located along the inside (medial side) of the arm. At the top, it attaches to the coracoid process on the anterior (front) part of the scapula bone or “shoulder blade” just below the shoulder joint. The muscle stretches along the medial (inner) part of the humerus bone of the arm, and it comes together with the long head of the biceps brachii to form the strong bicipital tendon. The bicipital tendon crosses the front part of the elbow joint and attaches on the radius bone of the forearm near the elbow joint. Contraction of the biceps muscle can pivot the radius bone at the elbow joint, and this supinates the hand (turns the palm toward the ceiling), if the hand begins in a pronated position
Brachialis Muscle
This muscle is a very important flexor of the elbow joint. It attaches along the anterior side of the humerus bone throughout its journey down the arm. It crosses the elbow joint anteriorly and attaches to the anterior side of the non-pivoting ulna bone of the forearm, near the elbow joint. The attachment to the ulna prevents the brachialis from having any role in supination. As much as 60 to 70 percent of forearm flexion is thought to be due to the strength of the brachialis muscle.
Machine Preacher Curls
In this exercise, the posterior arm rests on a “preacher” bench that looks a little like a pulpit that preachers/pastors stand behind to deliver their weekly message – hence the name of the exercise. The angle of the bench puts the arm position somewhat forward, which decreases the emphasis on the lateral head of the biceps while increasing the challenge for the medially-placed, short head biceps brachii muscles.
1. Sit comfortably on the seat. Until you get the “feel” of the exercise, adjust the weight stack to a light weight. Place your triceps along the top one-third of the bench. Do not jam your armpits (axilla) into the top edge of the bench because it is too easy to cheat from this position. Rather, your axilla should be above the edge of the bench and only your triceps should contact the bench.
2. Grip the handles firmly with a supinated (“palms up”) grip.
3. Flex your elbow joint (i.e., curl the weight) so that the handles move toward your face. The bench will prevent you from pulling the elbows posteriorly into arm flexion, thereby concentrating the efforts on the short head of the biceps.
4. Continue to curl the weight upward toward your face or nose as far as possible. Because your hands are supinated throughout the exercise, your biceps will be strongly activated throughout the range of motion.
5. Slowly lower the weight toward the floor as your elbow joint straightens. It is important to make this a slow descent and control the lowering of the weight (take 2-3 seconds to lower the weight). A fast descent, at best, will reduce the effectiveness of the exercise; at worst, it will result in injury to the elbow joint.
6. Stop the downward descent just before your elbow joint becomes completely straight, and then begin the curl back toward your face. This will maintain the tension on the biceps throughout the full range of motion.
7. Take a 60-90 second rest, and start your next set. Three total sets are enough for this exercise.
You do not need to use heavy weight, but it should not be that easy to complete 10-12 good repetitions. However, if you cannot completely control the weight during its descent, lower the resistance or stop the set to reduce risk of becoming injured.
Machine preacher bench curls will make you work harder than some arm exercises, because the bench prevents the arms from “cheating” to swing the weight up with torso body movement – as is often the case with barbell or dumbbell curls. However, the extra effort is certainly worth the outstanding results that will soon grace your arms. Sleek, sexy and firm upper arms will soon be a standout centerpiece for your newly reshaped upper body.
References:
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Oliveira AS and Goncalves M. Positioning During Resistance Elbow Flexor Exercise Affects Electromyographic Activity, Heart Rate, and Perceived Exertion. J Strength Cond Res, 23:1389-1397, 2009.
Oliveira AS, Goncalves M, Cardozo AC and Barbosa FS. Electromyographic fatigue threshold of the biceps brachii muscle during dynamic contraction. Electromyogr Clin Neurophysiol, 45: 167-175, 2005.
Moore, KL and AF Dalley. Clinically Orientated Anatomy. 4th Edition. Lippincott Williams & Wilkins, PJ Kelly, Editor. Baltimore, Philadelphia. pp. 720-723, 1999.
Sewright KA, Hubal MJ, Kearns A, Holbrook MT and Clarkson PM. Sex differences in response to maximal eccentric exercise. Med Sci Sports Exerc, 40: 242-251, 2008.
Yoon T, Schlinder DB, Griffith EE and Hunter SK. Mechanisms of fatigue differ after low- and high-force fatiguing contractions in men and women. Muscle Nerve, 36: 515-524, 2007.
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