For once, there may be something to a trendy piece of running advice. Meredith Dietz Meredith Dietz Senior Staff Writer Experience Meredith is a marathon runner and stand-up comedian. As Lifehacker’s Senior Staff Writer, she covers personal fitness tech, home gym equipment, and more. Read Full Bio April 23, 2026 We may earn a commission from links on this page. Credit: Zain bin Awais/Lifehacker/Getty Images Running is more popular than ever, and with an influx of new runners comes an influx of influencers offering up their advice—some of it helpful, some of it distinctly not . If you've spent any time scrolling through running-related videos, you've probably stumbled across a coach, athlete, or "runfluencer" insisting that you shut your mouth when you run. The advice to breathe through your nose while running is nothing new, but is it actually backed by science? The answer, as with most things in running, is nuanced.…