Place one hand on your chest near the upper sternum and another on the upper abdomen, just below the ribs. As you take a deep breath in, if the sternum hand moves first, before the lower abdominal pattern you’re likely using an in efficient pattern that leads to extra work, as well as neck and back tightness. Learn more about how breathing can impact your running here: https://www.therapeuticassociates.com/the-elephant-on-the-track-how-subtle-breathing-disorders-can-significantly-impact-your-training-and-race-potential/