Myth - You should stay anchored to the ground when you hit most of your shots.
Truth - Staying anchored to the ground may be good for golf, billiards, weightlifting, and fishing, but it does not work well in tennis. I love giving lessons to players who have been told over and over again to stay on the ground when hitting their shots. I love to see the expression on their face when I say, "I do not care if you jump off the ground or not, whatever it takes to make the shot, just let your body go!" Most of my students feel like a big burden has been lifted off of their shoulders and now they can relax, play tennis, and jump off the ground if they wish.
The pros jump off the ground on most of their groundstrokes, especially their power topspin shots. Jumping off the ground is a natural result of letting go and offers three important benefits.
1. More power
2. Improved fluency
3. Better balance
Jumping up causes a burst of impetus upward that adds power to your groundstrokes. Staying on the ground loses that extra power that can be beneficial in match play. Watch the pros as they jump off the ground in an attempt to hit harder and hit with more topspin on their groundstrokes.
If you hit a ball and let your body come to a screeching halt you will lose the fluency of that particular shot. If you let yourself go and your body leaves the ground the natural result will be a more fluid shot. Contrary to popular belief, jumping off the ground maintains fluency, it does not destroy it. If it did destroy fluency why would the pros be jumping all over the place on many of their shots?
Same principle as improved fluency. If you come to an abrupt stop while you are hitting the ball you will have a difficult time gaining your balance after the shot. If you let yourself go and jump off the ground when hitting, your balance will be more natural and much easier to maintain.
Here is the bottom line. The pros jump off the ground because they know instinctively that it is beneficial. You should do the same. Play without forcing yourself to stay on the ground and as a result jumping will occur naturally and instinctively. You will be playing and thinking like a pro!