training for speed?

[downsent]

Strong punches, and kicks for that matter come from form. I kickbox and at the gym I see 140 lb guys destroying the bag. It has to do with the pivoting of the feet and turning of the hips and shoulders while throwing the fist or leg.

 

[Lord_Suston]

Yo bro,
I box and wrestle, the problem is not that you aren't strong enough it is you are probably too inflexible, and are trying to punch with your arms and not your whole body.
Hitting the bag doesn't really get you any faster it just strengthens your joints for the impact. Try shadow boxing, since you will be solely working against your own muscles it will speed them up....
The only problem is you'll reach a certain point wherte you need to make a choice of being a fighter or a lifter.