The lead wrist controls the club face angle and the ball flight. Where the ball starts initially and the side spin.
Check out the photo below to see the 3 main wrist positions and what they mean:
1. The lead wrist is flat
A position which presents the clubface angle slightly closed. You need to be young. This is not a good position for the recreational golfer. Watch the young Tour player…but not all of them favor this position.
2. The cupped position
This represents a square position. Johnny Miller, Fred Couples and Phil Mickelson. Your hands and thumbs are under the club. Easy release.
3. Bowed lead wrist. A blocking position.
This requires a great deal of athletic ability and talent. Arnold Palmer, Lee Trevino, Sergio Garcia and Dustin Johnson. If you are over 40 a bump on your left wrist is not an ideal position to be in.
Use a mirror to check your lead wrist position. Remember this position determines your clubface angle at the start of the forward swing. Make sure your lead wrist represents your physical ability.