I thought a short explanation of a typical ventilatory response to the onset of exercise might help answer this question. Carbon dioxide in our blood increases at the onset of exercise at a greater rate than it does later during our exercise bout (after we’ve warmed up for a while). Respiration is what gets rid of this carbon dioxide, and thus our breathing rate also increases more than normal at the beginning of exercise. As exercise progresses, the chemical conditions of our blood (i.e. increased heat & metabolism) allow more oxygen to distribute carbon dioxide out of the blood, creating less demand for our breathing rate to do that.
Figure 1 presents the results of a study that observed the breathing responses to light, moderate, and heavy exercise. Each person in this study exercised at each of the aforementioned intensities for 5 min. You may have to study this graph a bit – but you’ll notice the initial increase in the rate of breathing (axis on the left) was less for lower intensities of exercise (represented by different line colors). I think this data helps provide the most likely solution to most people who question how to “get their breathing down when (they) first start running”. This simply means you just need to slow down (as represented by ‘light(er) intensity’ on the graph), and take longer to warm up. Even when I was fit enough to train 100 miles/week while running most my miles at 6:00 min/mile pace or faster I benefitted from walking the first bit of many of my runs. After walking for a while I would barely go faster for a bit (just enough to make a “jog”).
Depending on a person’s fitness level, a significant sensation of “shortness of breath” can occur at the onset of exercise. This is likely the result of exercising at too great of an exercise intensity for the person’s current level of fitness (more production of carbon dioxide than the body can get rid of by respiration – see first paragraph). They may also just need to take a longer time warming up. Figure 2 below demonstrates that your level of fitness can have a big effect on your rate and depth of breathing (called ‘ventilation’ in the graph).
Other breathing irregularities may also exist such as hyperventilation and asthma. Pulmonary illnesses (i.e. asthma, COPD, emphysema) can further cause breathing complications during exercise – but you’d have to consult with your doc about those.
By Trever Ball – Exercise Physiologist | Epidemiologist | Local Elite Athlete