I have some 1# weighted gloves (from softiron) that I use for many kickboxing workouts. My advice: don't use them for the warm-up or cooldown. Build up to using them through the entire "middle" of the workout, don't try to use them all at once your first time out. There is already a lot of stress on the shoulders and arms during fast boxing punches, and adding more weight increases that strength, but by more than just the weight, because the speed makes it feel heavier to your body (see Einstein about that). I recently got some 1.5# gloves, but I stayed with 1# for quite a while first.