A certain amount of breathlessness during exercise is normal, especially when engaging in a sport as demanding as running. Increased activity leads to faster breathing, which brings oxygen into the body to help lower building levels of carbon dioxide in the body during exercise. Once a normal level of carbon dioxide is reached, breathing usually returns to normal. Issues related to shortness of breath while running can be addressed by tweaking a routine slightly. When shortness of breath occurs suddenly or continues even after slowing down, it could be a sign of something more serious, so consult a doctor if symptoms don't improve after making changes to your exercise regimen.
Your warm-up is an important part of getting your body ready for any exercise you do, and you will struggle less with your breathing rate if you take the time to ease into your run. Start your run out slowly, jogging at a very easy pace or even walking, for at least 15 to 20 minutes before gradually increasing your speed. If it's cold and dry outside, a contraction of the smooth muscle of the airways leading to your lungs can occur, making breathing even more difficult, so be sure to take extra time to properly warm up in chilly weather.
Make sure you get enough air into your lungs when you breathe by focusing on proper breathing techniques. If you are breathing shallowly for too long, you risk hyperventilating. Keep as relaxed as possible and draw your breath deeply into your body. Anxiety can make your symptoms worse. To help keep the rest of your body relaxed while you are running, drop your shoulders down if you sense any upper-body tension. As you breathe more deeply on your runs, your diaphragm will become active, and you will notice your belly expand and contract as you inhale and exhale. Keep a regular breathing rhythm while you are running, inhaling two or three strides and exhaling one or two.
When you are running and notice shortness of breath, stop and walk or at least decrease the intensity of your activity until normal breathing returns. The higher the intensity of the workout, the more you risk losing your breath. If you experience persistent shortness of breath on your runs, schedule walk breaks before you have a chance to get out of breath. Take a one- or two-minute walk break between five- to ten-minute running periods. Make sure you are running comfortably before attempting to increase your speed, and avoid doing too many faster sessions during the week. Start with one day a week of gradually increasing your speed, and wait until you can manage a 10- or 20-minute tempo run without any breathing difficulty before you try to do any kind of high-intensity interval training.
It's natural to breathe harder when you run, but actual shortness of breath is a concern. It can be frightening and may require medical attention. If shortness of breath continues even after you have slowed down or stopped, or the shortness of breath is severe, make an appointment to see a doctor. Asthma, exercised induced asthma, allergies or other lung conditions can cause shortness of breath, so you should seek medical attention if your symptoms don't improve over time or by altering your running routine.