Main muscles worked
infraspinatus, teres minor
Capsule description
with a bent, fixed elbow, move its hand outward against resistance
This is an important exercise because it strengthens two commonly neglected articular muscles of the shoulder: infraspinatus, and teres minor, both of which rotate the humerus externally, or laterally, and also adduct it. The other two articular muscles are the subscapularis, which rotates the humerus internally, or medially; and the supraspinatus, which abducts the humerus only. The tendons of these four muscles fuse with tissues of the shoulder joint, at the rotator cuff.
The L-fly acts to reduce the strength imbalance between the external (weaker) and internal (stronger) rotator muscles of the shoulder. The internal rotators include the powerful pecs and lats. An excessive strength imbalance between the opposing external and internal rotators is a major contributing factor to shoulder problems.
To distinguish between the external and internal rotators of your humerus, imagine you’re shaking someone’s hand with your right hand. Keep your right elbow bent at a right angle, and your elbow fixed at your side. Moving your right hand to the right is external rotation, while moving your right hand to the left is internal rotation.
The L-fly has a small weight potential. A male novice may need a year or more to build up to using just ten pounds, and a female novice may need a year or more to build up to using just four or five pounds.
The use of small discs is critical, to ensure that progressive resistance is applied gradually.
Performance
Lie on your left side on a bench, and place your left hand on the floor, for stability. With a small plate or very light dumbbell in your right hand, form a 90-degree angle at your elbow—the L shape. Put your right elbow on your right oblique muscles, or hip, depending on your body structure. A folded towel placed in the hollow between your hip and rib cage may help you to maintain the correct elbow positioning. Lower the weight until your right forearm rests against your abs, then raise your right forearm as far as possible. Keep your right elbow fixed against your side throughout the set. Inhale on the descent, and exhale on the ascent. Finish the set, turn around, then work your left side.
Lying L-fly. Lift your forearm as near to vertical as possible.
Do the exercise slowly—three seconds for the lifting phase, a pause for a second at the top, a further three seconds for the lowering phase, a pause for a second at the bottom, then smoothly move into the next ascent.
Never train the L-fly to failure, never raise your elbow, and never roll backward even a little.
Variations
The L-fly can be performed while standing, using a cable or band that runs horizontally to the floor at about waist height. Stand sideways to the cable, right foot nearest the cable, your feet about hip-width apart, a single cable handle in your left hand, left elbow near your left side and bent at a right angle, and left forearm across your abdomen. Rest your right hand on your right hip or thigh. That’s the starting position. Slowly and smoothly move your left hand outward. Keep your left humerus vertical, left elbow near your left side, and left forearm parallel with the floor. Pause for a second at the point of fullest rotation, and smoothly and slowly return to the starting position. Pause for a second, then repeat.
Alternatively, use the cable from a floor pulley. Kneel on your heels on the floor, sideways to the pulley, and the midpoint of your thighs in line with the pulley. Space your knees for stability, keep your torso vertical, and perform the L-fly as described for the standing cable version. You may, however, need to keep the elbow of your working arm a little further away from your body, for better alignment with the direction of the cable, because the cable may not be horizontal to the floor, depending on the apparatus, and your size. Set your elbow position for the cable pathway that feels the most comfortable, and keep it fixed there throughout the set.
Cable L-fly, standing.
Take special care with any variation of the cable or pulley L-fly. The muscular tension arising from these forms of the L-fly is such that when your muscles tire, near the end of a set, it’s especially easy to lose the groove of a rep, and get injured. The dumbbell lying L-fly can be controlled better, and is safer.
Furthermore, depending on the minimum resistance of the cable or pulley arrangement, you may first need to build sufficient strength by using the lying L-fly, which can start from a tiny plate or other item. And incremental resistance isn’t possible with the type of cables that come in bands—to progress from one band to two, for example, is a huge jump. Incremental resistance can be applied to the lying L-fly, and the pulley L-fly.
Pulley L-fly, kneeling. If, when the pulley is lined up with the midpoint of your thighs, the resistance is too great at the minimum setting, you may be able to reduce it if you sit further back, depending on the design of the apparatus. If so, then as your strength increases, gradually move forward until the midpoint of your thighs is lined up with the pulley. Then increase the resistance with a tiny increment.
The L-fly acts to reduce the strength imbalance between the external (weaker) and internal (stronger) rotator muscles of the shoulders. An excessive strength imbalance between these opposing muscles is a major contributing factor to shoulder problems.