Medical experts say that climbing the stairs is an aerobic exercise that helps you burn calories by elevating your heart rate and it uses more muscles than other activities such as walking or jogging. Thus, it increases the rate of oxygen uptake required by the body, causing your heart and lungs to work harder in order to transport sufficient oxygen to your muscles especially to the muscles of the legs. When this happens, neither the lungs nor the heart is able to respond and the brain interprets this decreased oxygen delivery to the body as being out of breath.
However, while lack of exercise is the major factor that causes being out of breath after climbing the stairs, there are also some health conditions that could also cause it especially if you have a sudden onset of difficulty breathing doing routine, day-to-day activities. For example, diseases like high blood pressure can make you feel dizziness, fatigue or loss of balance, according to the American Heart Association.
To be on the safe side, ensure you exercise regularly so that your cardiovascular and respiratory systems can become strengthened and develop endurance, allowing you to perform more difficult activities for longer periods of time. Fortunately, climbing the stairs is good exercise for your legs so that your leg muscles can strengthen over time and reduce the amount of tiredness you feel after climbing stairs.
Thank you for reading! Love you.