The stance you use when hitting the ball determines the concentration needed concerning your shoulder turn. If you hit in the more conservative closed stance, where there is a turn step and hit, the shoulders will naturally turn sideways because the left leg (if right handed) is pointed toward the net.
On the backhand side, the shoulder turns are much more natural because the hand holding the racquet is in front of the body, so when the racquet is taken back you have to turn the shoulders. Whether you have a one or two handed backhand there is a natural shoulder rotation.
Now that the open stance has become more and more popular there is a greater risk of not enough rotation. Remember, the open stance is really only meaning from the hips on down, not the entire body. The torso must rotate to the side on your back swing.
We generate power from the backswing to contact with the forward shoulder rotation through the shot to the complete follow through. Our power also comes from the head speed that is generated by the upward wrist snap to create topspin.
The other problem that will stem from not enough shoulder turn is a late racquet head, or hit, causing the shot to be late, or wide. When we turn the shoulders the face of the racquet will stay facing the opponent’s side of the court more easily.
So, in review, if the stances are closed the shoulder turn, while still requiring attention, will turn more naturally. The backhand is definitely natural due to the mechanics of the stroke, in either the closed or open stance. The open stance forehand is the most likely shot to cause a late hit, or weak power, due to the fact the player may think the shoulders are turned because the racquet is back, but in reality the player still might be facing the net. So, be careful!!
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