I work my arms very hard in the offseason, but it has less to do with golf than it does with the fact that I had always done so while playing baseball. I have a number of exercises that are not found in most golf training programs but have helped me greatly increase my bat speed.

First: you need a partner and a heavy medicine ball. You stand back to back with your partner, hold the medicine ball with both hands in front of your body, and rotate your trunk so that you are passing the ball to the person behind you. Once releasing you rotate you empty hands to the opposite side of your body to receive the ball in the same manner you handed it off. In essence you are just making the ball orbit the two of you, but you are doing it as fast as possible. Do this for 75 laps one direction then start passing the ball in the other direction for another 75 laps. This will build your trunk and obliques and greatly improve your range of motion in your upper body.

Wrist curls and reverse wrist curls have greatly improve my club control and has greatly improved the position of my front wrist at impact. I used to get very wristy when hitting the ball, but now my lead wrist is always flat at impact.

I have fond that I have trouble keeping my left arm straight on my backswing and cocking my wrists at the top of my swing when I work my biceps and triceps hard, but the greater control and power greatly outweigh the benefits of perfect form.