all that is retarded, any movement should work directly against gravity with your body perpendicurar to the angle of motion for stability. since cables do not work with gravity it isn't as intuitive however the fact remains the same: if you want the target muscle to get 100% of the stress you have to angle your body to be in good posistion. for cable cross that means 1. bend over (like bent over rows (same position)) and do it that way or 2. when the pulley is set low it would be much more beneficial to use an incline bench and sit in it for back support.