I train MMA athletes. This is a sport that requires endurance and speed. The AAS increases the muscular strength to increase power movements. Power, being defined as how quickly you can exert all of your strength/force. The faster you can deliver a punch full force the more power you're going to generate and more energy you'll transfer to your opponent. I've seen my athlete's performance increase while on Anavar, Test, and other AAS compounds. It's not a dramatic increase in performance, these guys are already top athletes, but it's enough to be noticeable.