Just watching a bit of the ladies in the US open, it strikes me that on serve the receivers all have their feet wide apart. I would have thought that to be prepared to take a serve wide to the forehand or backhand, the best way of reaching it would be with feet at most shoulder width apart, allowing more “spring” from the opposite leg.
I’m clearly wrong though as they all seem to do this. Any thoughts?
I am not a biomechanics expert but I would say it lowers the center of gravity for quicker lateral movement; also, they’ll already be inches closer to the ball on either side just by leaning onto the appropriate leg. Basketball and American-football players take a similar crouching posture with a wide stance when attempting to stay in front of a ball handler who can dart quickly to either side.
When you push off, the force follows a line from your foot through your center of gravity, so you don’t rotate. The wider and lower you are, the more that line goes from side to side, rather than up and down.