Trainers perform dumbbell fly presses by lying on a bench with arms extended above the body while holding a dumbbell in each hand. Elbows are then slightly bent before the trainer proceeds to lower arms to the sides of the bench until dumbbells are chest level. After holding that position for several seconds, the arms are then raised in a "hugging" motion by squeezing pectorals and utilizing shoulder and upper arm muscles. Dumbbell fly presses also expand the thoracic region because of the way weights are held out and sustained by core muscles.
Pectoralis Major
The target muscle of dumbbell fly presses is the pectoralis major, a thick muscle shaped like a half-circle located in the chest anterior. The part of the chest in men that bulks up during weight training is the pectoralis major. Responsible for medially rotating and adducting the arm, the pectoralis major also assists in breathing because it helps to pull ribs upwards during inhalation. This muscle is worked out during bench presses but is isolated when utilized throughout performance of dumbbell fly presses.
Anterior Deltoid
As a synergist muscle used in the dumbbell fly press, the anterior deltoid functions to move the arm to the front and away from the body. As a member of a three-part group of muscles which includes the posterior and lateral deltoid, the anterior deltoid is given a workout during the dumbbell fly press when the trainer raises his arms above him while holding dumbbell weights. The anterior deltoid effectively performs it function at this point, with enhancement provided by weight resistance.
Biceps Brachii, Short Head
The biceps brachii short head is another synergist muscle employed by the dumbbell fly press exercise. The biceps brachii short head is one of the heads of the biceps brachii, located on the inside front of the upper arm. Elbow flexion is facilitated by the biceps brachii short head, as well as forearm supination. Pullups and rowing also recruit this muscle, as well as certain workouts emphasizing back muscles. In addition to the dumbbell fly press, preacher curls also effectively emphasize the short head biceps brachii while simultaneously de-emphasizing the long head bicep.
Stabilizer Muscles
These muscles include wrist flexors, brachialis, triceps brachii and biceps brachii. Wrist muscles -- the flexor carpi ulnaris and the flexor carpi radialis -- permit wrist flexion and contribute strength during the "hugging" motion of the dumbbell fly press. The triceps are a three-headed muscle lying at the back of the upper arm and assist in extending the elbow joint. Also situated in the upper arm is the brachialis, a muscle responsible for elbow flexion. The brachialis is also considered a synergist because it helps biceps to flex the elbow as well.
References
- ExRx.Net: Dumbbell Fly
- "Bodybuilding Anatomy"; Nicholas Evans; October 2006
- "Strength Training Anatomy"; Frederic Delavier; September 2001
- MyFit.ca: Dumbbell Fly's
- "ACSM's Resources for the Personal Trainer"; American College of Sports Medicine; 2007
- ExRx.net: Pectoralis Major (Sternal Head)
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