Q: What causes shortness of breath and discomfort in the lung/chest area (not pain) at the beginning of a run, however slowly one runs, when the shortness and discomfort leaves after running for awhile? - Carol
A: Oh this is an excellent and oh-so-common question Carol! Many clients ask me why they have a hard time catching their breath at the start of the run yet they feel like they can keep going and going once they are 10 minutes into it. It all comes down to something known as the 'Oxygen Deficit' in the land of exercise physiology.
When we start exercising and transition from rest to light exercise, there is a gradual increase in oxygen uptake. It takes time to supply your working muscles with blood (which carries the necessary oxygen and nutrients) and is observed by an increase in your heart rate and breathing rate at the start of your workout.
It takes approximately 1-4 minutes to reach a steady state of oxygen uptake but this can be longer in certain individuals or circumstances. The time required to reach a steady state increases at higher work rates and is longer in untrained individuals than in aerobically trained individuals. Individuals with compromised lung function such as those with asthma and respiratory illness will also require additional time to reach a steady aerobic state.
Because oxygen uptake does not occur instantaneously, there is a period of time where your body is incurring an 'Oxygen Deficit'. Not enough oxygen in the bank. So, your body turns to its anaerobic metabolism to provide the required energy at the start of your workout. Once a steady state of oxygen uptake is obtained, however, your energy is provided through your aerobic system. The term 'Oxygen Deficit' is used to describe inadequate oxygen consumption at the onset of exercise. Make sense?
So, what to do? Slow down and increase the length of your warm up. Your body is telling you that you are working too hard at the start of your workout if your breathing rate spikes or your legs are burning. You may need to walk for 5-10minutes before very gradually increasing to a jogging pace. You may need to jog slower than the others in your group. You may need to warm up 20 minutes before races. And that's OK. The important thing is identifying your body's needs and providing it with a personalized warm up. Otherwise you may suffer further into your run and speed up your time to fatigue during hard efforts. And we don't want that. So, slow down to speed up!
Hope that answers your question!