[France_is_bacon]

This is true. As someone who has done a lot of sparring, I can go for a long time, but it is only because I have learned how to be perfectly relaxed. Most people tense up their whole body and stay that way. Also breathing is incredibly important. But mostly, it is keeping your body relaxed, which also relaxes the breathing. But that's extremely difficult to do, when one hasn't done it thousands of times.