Raise your racquet hand straight up as high as you can. Stretch it higher even more. With you arm locked straight up, you'll notice you can slide your arm up and down by around 3 inches. You can notice the same thing by shrugging your shoulders up and down. Normally when I smash, I push my shoulders up while the racquet is at the highest point with my arm up, and then pull my shoulder down while the racquet is moving down, creating a whip-like effect. I've noticed that using the whip effect, my lighter racquets are much more powerful at smashes than my heavier racquets. Since i've been injured however, I've been forced to keep the shoulder still during smashes. Under this condition, the heavier racquets produced much faster smashes than the ligher racquets, but still slower than lighter racquets using the shrug-reverseshrug method. I don't remember hearing about this often. Do you guys shrug-reverseshrug when you smash? Do you smash better with heavy or light racquets? ps. I think the muscles i'm talking about are the upper and lower fibers of the trapezius, but I could be way off too.