The only way to isolate specific back muscles - whether it is upper. or lower back - or make any progress is through the power of the mind-muscle connection.
Lee HaneyRule of thumb: Eat for what you're going to be doing, and not for what you have done. Don't take in more than you're willing to burn off.
Lee HaneyExercise to stimulate, not to annihilate. The world wasn't formed in a day, and neither were we. Set small goals and build upon them.
Lee Haney