I recently lost a match, with some guy, becausei burned out after 10 minutes, was it because of junkfood or?

Sounds like you need to work on endurance. Elastic bands are a great way to build muscle strength and endurance using weights or just them. Muscle and Fitness has whole programs designed strictly for them. Legs, core, arms, shoulders, anything muscle wise. Also try taking beta-alanine. It increases muscle carnosine levels which is a functionally active peptide that has antioxidant properties and is a big muscle fatigue controlling factor. Its a supplement, not a drug so don't worry about urine tests. If you do decide to take it, understand that there may be a tingling; don't be alarmed its just doing its thing with the nerves. No harm, I promise but follow the directions on the bottles!! :D