The cable crossover, also knows as cable fly, is an isolation chest exercise that works on your pectoralis muscle, major and minor.
This is a great chest exercise because it stretches the pecs from the start position, hitting the outer pec muscle fibers, allowing you full range of motion. Depending on the position of the cable you can target your lower or upper pecs.
The cable crossover is a similar to dumbbell flyes, But a huge benefit of the cable, is that it allows a steady resistance trough the full range of motion. The dumbbell variation, because of gravity, will only produce significant tension on the pecs in the bottom half of the range of motion. Using a cable on the other hand will give you steady resistance throughout the whole movement, working your pecs also at the top of the movement to keep the cables from pulling apart.
Another major advantage of the cable crossover is that you don’t perform it on a bench. The shoulder blades - scapulae, are free to move in a natural manner without being pinned to a bench.
Since this exercise done standing up, it will also require a lot of work from your core muscles to stabilize your torso against the cables weight pulling you back.
Your pulley position is determined by the area of the chest you want to target. Setting the pulleys in the highest position focuses on the lower pecs, while the lowest position will work your upper pecs. Placing the pulleys at shoulder height—with arms parallel to the floor—will target your middle pec fibers.
Keep Your Shoulders Back. If you find you are thrusting your shoulders forward as you complete the exercise, you are working your shoulders and back, not your chest. It might also indicate you are using too much weight.
Allow only slight bent on your arms, bending your arms will make the exercise easier, but also much less effective. Keep your arms straight but don't lock your elbows, and if you are having trouble use lighter weight.
Keep an eye for shoulder pain. Even though the cable crossover movement is more natural than a dumbbell flye or bench press, your shoulder still may not tolerate it. This depends on your previous injuries. it is better to looks for a different exercise if you feel shoulder pain after doing it.