I know there is always someone who says some professional athelete is using a certain substance, but I have heard of IGF being used by boxers before and HGH for that matter, right up to the date of the fight. I have heard of martial artists using it and many atheletes where speed and strength is an advantage, what protocol to use might vary because IGF is such a powerful growth factor and it's use can be limited due to receptor downgrade. As far as I am aware it is also undetectable in drug testing. As in the case of a heavyweight, the chances are with the correct training regime and diet, it could cut your bodyfat down and increase lean mass hopefully the faster twitch muscle fibres.