Are you taking in air via nose or mouth while running? There are so much controversial out there regarding to the running breathing technique. The best answer should be pick up the technique that you feel most comfortable with since no one understand your body better than yourself. A simple rule is, breathing via your mouth while running in high intensity since it helps to take more air in, while you doing a long run say half or full marathon at a slower pace, you can breath via nose. Breathing via nose help you to be able to talk while running, even carry on the full sentence in your conversation.