Huffing and puffing after climbing a few flights of stairs isn’t cause for concern. Dr. Catherine Myers, a pulmonologist with the Northwestern Medicine Canning Thoracic Institute in Chicago, says that “it’s pretty normal to get temporarily short of breath.”

“You need to deliver more oxygen to your tissues because you’re using more of your body,” she tells theSkimm. Climbing stairs involves muscles you don’t usually use when walking, so you may be out of breath after a few flights but should recover quickly, says the expert.

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Shortness of breath, also called dyspnea, results when your heart and lungs are working hard. Your lungs help get oxygen to your blood while your heart pumps oxygenated blood throughout the body, according to Health. Ascending stairs affects your heart and lung endurance.

Going up a flight of stairs forces your leg muscles to move your body weight. Researchers say that continuously climbing stairs requires nine times the energy needed for sitting.

However, if you experience shortness of breath after only a few steps and do not recover quickly, it may be time to seek medical help. Physicians may look for signs of asthma, COPD, or other heart or lung issues. The quality of your environment — like dusty air of high altitudes — can also affect your ability to breathe easily.

If you are medically sound and still have trouble climbing stairs, you may want to work on endurance, says Myers. This means stepping up your workout by walking or running on an incline. Here are other ways to build endurance:

• Climb more stairs. Climbing more stairs gets your muscles used to the movement and increases their efficiency. Experts suggest using intervals to step up your fitness. This means taking one flight of stairs at a normal pace and then speeding it up for the second flight. “Ultimately, how efficient you are in taking in oxygen and using it will allow you to do something as intense as climbing stairs for longer,” Frank Baptiste, founder of Frankly Fitness, told Health.

• Squats. You can also strengthen your legs by performing squats. Stand with feet shoulder-width apart, chest high and arms clasped in front of you. Squat deep, bringing your hips and knees parallel. Make sure your knees stay behind your toes. Stand up and repeat three to four sets, holding each squat for 30 seconds.

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• Step-ups. Stand behind a low bench and step into the bench with your right foot. Bring your left foot to meet the right and then step back down with your right. You can add light dumbbells to make this exercise more challenging. Repeat four sets of 10 step-ups, changing the lead leg with each set.

• Toe taps. To increase cardiovascular endurance, place a ball or low bench in front of you. Tap your right toe on the object and switch feet as you jump in the air, tapping the left to on the ball or box. Repeat for 20 seconds, rest for 10, and then repeat the sequence.

Other activities such as ballroom dancing, Nordic walking, biking, rowing and running can also help boost your endurance level and strength.

Always check with a healthcare professional before embarking on any exercise regime to ensure your safety.