Have been able to spar with a guy in BJJ who was a former (couple years ago) Offensive Tackle for a very successful college football team. I'm about 180 lbs and he's about 300+ lbs and has an incredible amount of strength from being more or less a professional athlete. I'm able to hold my own against him and at times we seem evenly matched. This goes to show you that training in martial arts is no joke. Most hooligans you encounter will not be this big/strong, so imagine how much more power you would have even against someone your own size. Remember, if you train hard you can fight easy. I do hope nobody here will ever need to employ any kind of martial arts for self-defense, but you should never be caught lacking.