Chest pain that occurs while running may have a variety of causes, says David Friedman , M.D., chief of heart failure services at Long Island Jewish Valley Stream Hospital. While its important not to ignore pain, not all chest pain while running is cause for concern.

Chest pain or chest pressure during exercise can occur in recreational runners as well as in athletes who are in excellent shape, says Jennifer Mieres, M.D., professor of cardiology at the Zucker School of Medicine at Hofstra. "There are many possible causes which span the spectrum from benign to life threatening, so it's important for everyone who exercises to be able to recognize the signs and symptoms that indicate when chest pain or pressure during a run is a marker of a potentially serious issue such as heart disease or asthma."

Ok, noted. In order from least to most severe, here are the five most common reasons why your chest could hurt during a run, plus what to do if you think you're experiencing them.

1. Youre new to running.

Jumping into a new jogging routine can be physically taxing-especially when youre a rookie. If you havent had much training in the sport, it could be that youre working out at a rate or intensity that your body isnt accustomed to yet.

You need to back off and be more realistic about what youre trying to accomplish, says Janet Hamilton, C.S.C.S., exercise physiologist and lead running coach for Running Strong in Atlanta. She suggests warming up with a walk , then easing your way into a relaxed running pace. If you can recite the pledge of allegiance as youre running, then youre probably running at the right effort, she says. If youre having a hard time chatting, slow down.

Heavy respiration during a run may be painful at first, but the strain typically goes away with consistent practice . Also, it goes without saying that any new workout regimen youre considering should be cleared by your doctor first.

2. The muscles in your chest are cramping.

Just like the muscles in your legs, the muscles surrounding your rib cage (called intercostal muscles ) are also prone to cramping while youre pounding the pavement. This sharp pain is highly localized-meaning you can usually put a finger on exactly where it hurts-and might worsen with movement. According to Friedman, dehydration or electrolyte depletion could be the culprits behind the spasms.

Since theres not much you can do to strengthen your intercostal muscles anyway, try refueling with some water and changing up your breathing pattern. If you tend to breathe on a symmetrical rhythm (for example, in for two steps, out for two), you may want to play with breathing in an asymmetrical rhythm (inhale for two steps, exhale for three) so that youre constantly switching which leg is in weight-bearing position when breathing is initiated, says Hamilton.

3. You have heartburn.

You may not realize it, but jogging piles a ton of pressure onto your digestive system . For one thing, Friedman explains, the increased tension within the abdomen causes the esophageal sphincter (the muscle at the bottom of the esophagus that keeps your stomach contents from rising into your throat) to relax, contributing to heartburn.

To ease the burn and keep your food in your stomach where it belongs, Friedman advises forgoing heavy meals before runs. If you do eat prior to hitting the road, stay away from trigger foods-that is, anything spicy, fried, or caffeinated. You may also want to monitor the foods you consume before runs to determine if a particular food doesnt sit well with you, says Hamilton. If youre burping if you run after eating a banana, then switch to something else as your pre-run snack .

4. You have an unaddressed lung condition, like asthma.

Heres where things get dicey. There are a few different pulmonary issues that can spark pain during a sprint, the most common of which is asthma . Pre-workout medication can help prevent an exercise-induced asthma attack, and a rescue inhaler should always be kept on hand during a run if youre a diagnosed asthmatic . If you dont quickly respond to your inhaler, this could signify worsening breathing mechanics and the need for urgent care, says Friedman. Stop running and if you do not get relief within a few minutes, and have symptoms of shortness of breath and wheezing, consult your doctor, notes Mieres. If symptoms progress, call 911.

Other dangerous-but less common-causes include pneumothorax (a leakage of air into the space between the lungs and the chest wall) and pulmonary embolism (a blood clot in an artery supplying the lungs). Both of these are often paired with a sudden onset of severe pain and shortness of breath, which doesnt go away with rest. If you see these red flags, dont ignore them; get the help of a doctor right away.

5. Youre having heart complications, like heart disease, heart attack, or angina.

Now for the worst-case scenario. You already know that the harder you run, the harder your heart has to work. But if your coronary arteries-which bring blood to your ticker-contract, the insufficient blood supply can induce chest pain when you exercise. This condition is known as angina , and should resolve after a few minutes of rest (though you should definitely still follow up with your doc, says Mieres). And, of course, physical strain can also prompt a heart attack (an acute blockage of a coronary artery) or an arterial tear. Accelerating and worsening chest pain, pain in the jaw, back, left arm or other parts of the upper body, heavy sweating, nausea, vomiting, shortness of breath, significant palpitations, and/or dizziness that worsens with high-intensity activity but is relieved with rest are all indications that something could be signs of a heart attack, Friedman adds. Call 911 right away if you experience these symptoms.

If you have even the slightest suspicion that your ticker isnt ticking quite right, the best thing to do is book it straight to your physicians office. When in doubt, go get checked out! The worst youll experience is some expense and some embarrassment if it turns out it was nothing life-threatening, says Hamilton. If it was something serious, you may have just saved your own life.