Breathing is automatic: awake or asleep, running or resting, our bodies unconsciously make sure we get enough oxygen to function. But - unlike other bodily functions such as heart rate and digestion - it’s not hard to control our breathing consciously. If you’ve ever been to an exercise, meditation or yoga class, you’re probably familiar with instructions about how and when to breathe. It was one of these instructions - “breathe in through your nose and out through your mouth” - that prompted CrowdScience listener Judi to wonder if this really was the best way to breathe during her exercise class. Is there good evidence to support the benefits of different breathing techniques - whether through the nose or mouth, fast or slow, noisy or quiet? And is consciously controlling your breath more about improving psychological focus, or optimising body mechanics? Sports scientist Mitch Lomax takes us through the biology, chemistry and physics of breathing, and shows us how to train our respiratory muscles. We meet yoga guru Hansa Yogendra in India, where the study of pranayama - literally “breath control” in Sanskrit - is thousands of years old; and find out what scientists have discovered about the effects of these ancient techniques on the body and mind. Presenter: Anand Jagatia. Producer: Cathy Edwards (Photo: A woman jogging outside, wearing sports clothes on a blue sky background. Credit: Getty Images)