Sitting on the machine, feet firmly on the ground, knees at 90 °, the exercise consists of bringing the arms (elbows slightly bent) in front of you.
This exercise is a variation of the supine spreads where you find yourself lying on a bench instead of sitting on a bench.
To work your pectorals properly, you need to place your elbows in line (axis) of your shoulders.
Depending on the type of device you are using, you have a choice of how far you want to go. Too large amplitudes should be avoided to protect your shoulders. You will avoid going further back than your shoulders.
Also, and this goes for all chest exercises, keep your rib cage wide open throughout the exercise. This way you will avoid bringing your shoulders forward.
Consider inhaling as the rib cage opens (when your arms come back) and exhaling when your arms are going forward.
Be careful not to have your arms stretched too far, which increases the risk of injury to the biceps.
Secondary: shoulders (anterior bundles), triceps, biceps
Interest of Butterfly pectoral machine
The machine spreads are more secure than the different versions of the dumbbell spreads. The machine guides the movement and prevents “false movement”.
However, depending on the machine, the resistance can be more or less continuous making the exercise more or less effective.
Variants of butterfly pectoral machine
Depending on the room, the exercise may be performed on a machine that requires you to have your arms bent (forearms vertical).
Danger / Contraindication of butterfly pectoral machine
By keeping the arms straight, the biceps are stretched at the level of their two insertions which places them in a position of “weakness”.
So bend your elbows.
Also, watch your shoulders, they may not appreciate the stretch this exercise causes. In this case, you will need to reduce the amplitude.