Alot of times when I'm playing tennis, I will run around my backhand and hit an air forehand. That is, when I uncoil I come off the ground alot like you see Federer doing in this video:http://www.youtube.com/watch?v=C3EaGo4rhKk Now when I land, I land on my left foot such that it really stretches my left Achilles tendon. You can see what I mean in the video above as Fed lands on his left foot. I doubt it bothers him but when I do it (our mechanics are probably very different), the way I land makes my left Achilles kind of tender. I'm not sure how else to explain it. Any thoughts on this? Would an ankle brace help?