The method described by jhocking is very powerful and flexible and allows you to merge all sorts of upper/lower body animation. This is one of the benefits of skeletal animation.
The easy alternative would be to just create a running/reload sequence -trigger this as a one-shot anim when the user hits the reload button - preferable on the last frame of the normal running sequence so there are no transition glitches and then return to the normal running sequence.
The easy alternative would be to just create a running/reload sequence -trigger this as a one-shot anim when the user hits the reload button - preferable on the last frame of the normal running sequence so there are no transition glitches and then return to the normal running sequence.