Jumpsoles aren't that special. You know that the fast-twitch muscle fibers in your lower leg aren't even close to as important they are in your upper leg. Jumpsoles just place stress on the ball of your foot which in turn places stress on the gastrocnemius(calf muscle). You think the calf muslces are the primary importance in jumping? they're not. Stand with you're legs straight, and try to jump up without bending your knees, and just with the power of your calves. You will probably get up an inch or two. That's how much the calves are involved in jumping vertically. If you did the same with your upper legs, it is much different. If you think that jumpsoles are better than plyometrics, you're just being fooled. Although you get most of your vertical improvment from the plyometrics program given to you with the shoes.