When I did Taekwondo as a kid, I learned the parts of your foot you use for various kicks. It went something like this: Ball of the foot - front kick Heel - side kick, ax kick, back kick, spinning heel kick Blade of the foot - side kick, crescent kick (inside-outside), back kick Ridge of the foot - crescent kick (outside-inside) Instep - roundhouse kick However, I'm starting to learn the power of the ball of the foot. My Master at my current school has corrected me several times on different kicks that I should be using the ball of my foot. This has led to me successfully breaking boards that I was failing to with my old training. Kicks I now do with the ball of the foot are: Axe kick Outside-inside crescent kick (still do inside-outside with the blade or heel) Hook kick I haven't applied it to the roundhouse kick like I've seen some suggest, as I think it's too easy to catch your toes that way. I also haven't applied it to side kick or back kick (on purpose) because I feel the heel is more inline with the donkey-style kicks. However, I've noticed that using the ball of the foot I have more reach and more strength. I think the reason I used to treat the ball of the foot as weaker, is because of side kick and back kick. In those kicks, the heel has the best line with your power direction. (That's also why I think some people prefer to front snap kick with the heel). This is also the case with the front push kick. However, the heel isn't any more in-line with an ax kick or spinning hook kick than the heel is. It's essentially a longer piece of the whip. You're still striking with a bone, and a bone that's designed to be stood on. You're still striking with the same motion, just using a different part of your foot. I used to think the ball of the foot was the equivalent of a slap, but now I've come to think of it more like a punch. I've grown a much healthier respect for this part of the foot lately.