Cable flys are a machine exercise that primarily targets the chest and to a lesser degree also targets the shoulders, biceps and middle back.
Step 1: Stand between two high pulley cables with handle attachments.
Step 2: Hold handles with an overhand grip (palms facing down). Walk forward as you walk forward you will notice that the hands will drop to chest level. That is your proper starting position for the cable fly. Stand upright in a staggered stance with arms outstretched but slightly bent so that knuckles are facing forward.. This is the starting position.
Step 3: The best way to ensure proper muscular activation related to the exercise you’re doing and to prevent injury is to position your elbows at a hug position and slightly bent and move forward into what we would call a slap position with the arms not touching. Pause, then slowly reverse movement back to starting position. This completes one rep.
Pro Tip! Because cable flys use long levers, the goal should never be to use a significant amount of weight at the beginning. It really is a supplemental personal training exercise for the primary muscles which would be the chest.