Hey All, I'm trying to figure out the problem I have of 'gassing out' while rolling. I'm relatively new to BJJ and during the class, I start to gas. My breathing gets heavier and shorter. My muscles don't hurt, it's mostly my respirtory system needs air into my lungs. Is this a lack of Stamina or Endurance? I train 4 days a week for 1 hour. The guys in class tell me I need to start running on my days off.