A doctor once asked me if I ever get breathless when running. I had to explain that getting breathless was as much a part of running as putting one foot in front of the other, and failing to become breathless almost certainly meant that the run was having little benefit. Indeed my former professor from my student days at Loughborough University use to stress that running at a “tolerable” level of breathlessness was the optimal training intensity for most runs – anything less was too easy, and anything more too hard.
More energy demands more ventilation
When we run, the volume of air that goes in and out of the lungs (our ventilation rate) can increase from around 30 litres of air per minute at rest, to over 100 litres per minute. Approximately one fifth, or 21 percent, of this air consists of all-important oxygen, which the body needs to convert our stores of fat and carbohydrate into energy. During the very brief period of time when the air is in the lungs, some of the oxygen is transported across membranes into the blood stream, so that when the air leaves the lungs, the oxygen content has dropped from 21 to around 16 percent. As we run faster, our body demands more energy, which triggers a need for more oxygen and an increase in ventilation.
How to increase ventilation?
There are two simple ways of increasing ventilation and getting more air and oxygen into the lungs. The first is to take more breaths, and the second is to take in more air with each breath (changing what physiologists call “tidal volume” – often referred to as breathing more deeply. Perhaps surprisingly, when we run faster, we actually increase our breathing rate, but decrease tidal volume, taking in less air – not more – per breath. The body regulates the rate and depth of breathing to ensure that the volume of air that goes into the lungs, and the time that it spends there, is optimised to ensure that the most efficient transfer of oxygen into the blood stream can occur.
Your body knows your breath
Over the years, some coaches and scientists have tried to “coach” breathing techniques for runners, whereas the reality is that in this area, the “body knows best”, and simply relaxing and allowing your body to breathe in a manner that “feels right”, is the normally the best policy. However there are times during “steady state” running, when a constant speed is sustained over a flat surface, that running and breathing can be regulated so that they are synchronised – for example a rhythm of one breath every four or five strides can often work well – but this should occur naturally and never be forced. Deliberately trying to take deeper or shallower breaths, or forcing the body to take more or fewer breaths, can easily disrupt the body’s natural breathing pattern, and lead to a decrease in oxygen transport to the blood stream and muscles, not an increase. As well as responding to an increase in the demand for energy, ventilation during exercise is also controlled by the level of carbon dioxide in the blood, which needs to travel in the opposite direction to oxygen, leaving the lungs in the air that is exhaled. If this loss of carbon dioxide is impaired by disruption to breathing frequency and tidal volume, it can quickly result in fatigue.
So the simple solution is to “embrace” breathlessness” when running, relax and allow your body to naturally control and regulate how you breathe. Interfering could quickly impact on a process that works well, and ultimately make you even more, not less, breathless!
See also our blog "I will tell you the secrets of running fast"