Feeling breathless at the top of a flight of stairs happens to the best of us. I’ve run marathons, you might think to yourself. Why is this so hard? Well, you’re not alone. Amelia Boone, an ultrarunner and four-time world champion obstacle racer, even tweeted about having a hard time walking up to the fifth floor of her office.
So what’s the deal with shortness of breath after taking the steps? We talked to top experts to find out.
Why You Get Winded
What’s going on in your body when you run is different from what happens when you climb stairs, and it has to do with slow-twitch versus fast-twitch muscle fibers, explains Dr. Timothy J. Michael, professor of exercise science at Western Michigan University and a certified exercise physiologist.
First, a quick refresher on the science: Each muscle has individual muscle fibers, of which there are two main types—slow-twitch and fast-twitch. Slow-twitch muscle fibers have a high resistance to fatigue and like long-distance running for an extended period of time. Fast-twitch muscle fibers, on the other hand, come into play when you’re doing something that requires quick, powerful movements such as sprinting or jumping and tire faster than slow-twitch fibers.
“[Running] mainly relies on slow-twitch fibers, which are used for endurance and rely on “The slow-twitch fiber is high in endurance and fatigue resistance but low in power and strength. While climbing stairs can be an endurance activity, to propel your body vertically takes more strength and power, thus requiring more fast-twitch fibers to be recruited to accomplish the task.”
Plus, endurance athletes have an increased sensitivity to carbon dioxide and hydrogen, which are produced during anaerobic metabolism, accumulate the more you’re in motion, and make you fatigue faster, according to Frank Wyatt, a certified exercise physiologist and professor in the Department of Athletic Training and Exercise Physiology at Midwestern State University. This means you might start breathing heavier sooner than someone who gets very little exercise.
And if you’re breaking a sweat, that doesn’t mean you’re out of shape. Fit people actually sweat sooner and longer than those who don’t work out regularly. Sweating is your body’s way of cooling itself off, according to Wyatt. “If you are a fit person, the sweating response to aid in cooling the body is quicker and more prolonged when compared to an unfit person.”