Shortness of Breath
While it is normal to feel short of breath with heavy exertion, such as running up a hill, it can be a sign of other problems especially if occurring at rest or with moderate efforts. Consider the environmental conditions below.
High altitude is typically considered to begin at 8,000 feet although you may feel some effects at lower elevations. Most of the dangerous complications of altitude occur at over 10-12,000 feet. If you are racing at altitude, regardless of acclimatization you are at risk. You are at increased risk without acclimatization. It can be normal to feel more short of breath while running at altitude than at sea level but consider:
Do you feel short of breath at rest?
If so consider descending and if symptoms do not improve seek medical care
Do you have a cough and shortness of breath?
If yes consider the severity of your symptoms. If you are coughing up pink tinged or white phlegm or feel substantially short or breath you are at risk for High Altitude Pulmonary Edema (HAPE) and should descend NOTE: Exertion free descent is important with suspicion of HAPE do not push hard to descend.
What color is the skin?
If you see a purplish discoloration, especially notable around the lips you should descend and recheck. This suggests your oxygen level is too low.
In Cold Temperatures
Cold, dry air can irritate the airways and make you feel short of breath and cough. While this is not typically dangerous, it can cause temporary and potentially longer term damage to lungs if very cold or prolonged. Consider using a warming, humidifying mask device if anticipating these conditions. A neck gaitor or Buff can also serve this purpose
In Hot Temperatures
Consider your hydration status. If overhydrated you can develop hyponatremia (low sodium) and fluid can build up in your lungs. You may develop a cough with this as well that produce clear or white phlegm. Often other symptoms will develop such as nausea and dizziness. Look for other signs such as swelling in the hands or legs or weight gain. If this occurs you should stop and rest. While stopped don’t drink more water but you can drink a concentrated sodium solution such as 4 bullion cubes in 125mL water (you may want to flavor this as well).
With chest pain
Stop and seek medical attention
This may be related to too high effort for the conditions or your fitness. Slow down but if symptoms persist or occur while at rest you should seek medical attention.
Consider how you were feeling before the run? Have you been sick recently—fever, cough, etc.? If so you could be developing a more significant respiratory infection and should likely stop. Do you have any previous medical problems such as heart disease or blood clots? If so take these into consideration.