^^^ that makes no sense. you are putting a hole into your muscle and injecting something foreign then working it out. you would be weaker in that muscle
and i'm not saying directly after a workout injecting, i'm saying say i work out my chest on monday at 5pm. then i would inject my pecs later that night or the next morning. get it out of the way and let it heal in time for my next chest workout in 4 or 5 days