The pec deck chest fly exercise, also called a butterfly, is used to isolate, stretch and develop the chest or pectoralis major muscles. The pectoralis minor muscles in the chest, the deltoid muscles in the shoulders, and the serratus muscles in the rib cage also benefit from pec deck chest fly exercises. It is considered to be one of the safest chest exercises done in the gym for two reasons: the machine resistance is adapted to your personal tolerance by using a simple pin to change the machine weight, and it requires very little balance, so a spotter is unnecessary. Beginners can use this simple exercise for strength training before proceeding to a more complex fitness routine.
How a Chest Fly Is Performed
Sit in the pec deck fly machine with your back and head flush against the backrest at all times. Place forearms at a 90-degree angle on arm pads, with upper arms parallel to the floor. Exhale and bring arms together by pushing them forward in an arc-like motion until the elbows meet, while squeezing the chest muscles. Hold this position for three to five seconds. Slowly and smoothly return to the starting position while inhaling. Be sure to fully stretch the chest muscles upon return to the starting position, but do not hyperextend the shoulders. Repeat, doing three sets of eight--10 or 12 repetitions.
What Not to Do
Do not make jerky or erratic arm movements; move in a smooth, controlled manner. Do not perform the exercise too fast; perform the repetitions slowly and consistently to involve all muscle fibers. Do not push arm pads with hands; use your elbows. Do not raise the shoulders upwards, towards the ears; keep shoulders level to avoid shoulder joint, back and neck involvement.
Always use proper body mechanics and follow the gym safety rules to gain the most benefits from this movement and any other exercise regime.