I've worked with golfers who have spent so much time in the gym to increase their power they have actually stiffened up by reducing their range of movement. Worse still, when the try to use this new found strength on the course they tense up in the belief they are using their muscles effectively. However, it's not just a matter of reduced movement that's the problem. The level of control demonstated by the game's greats is achieved through sensitivity. Tense muscles are not sensitive and reduce what you will feel through your hands, make it harder to get the right amount of power for each shot and eventually lead to injury.
Strength is a liability if coordination is missing. Top players of all sports have poise, coordination and, as a result, are sensitive to what is required at each moment of a game and better able to carry out the actions necessary to meet those requirements. Golf strengthening programs can help, but only if you know how to use your new strength out on the course.
Also see A Poised Golfer Is A Happy Golfer.