A nice pair of lungs March 20 2015, 0 Comments

In a previous blog I mentioned whooping for air after doing some intervals, and that got me to thinking about the whole area of lung capacity and stamina.

Our capacity to take in oxygen and get rid of carbon dioxide depends on our lungs and our circulatory system.  Our lungs have a total capacity of normally about six litres for men and four for women, and at rest we use about 10% of this to breathe, the in- and out-flow being called the tidal volume.  The 'vital capacity' of the lungs is the maximum volume that we can breathe out after a full inhalation, and this is about 4.8 litres for a man, and 3.2 for a woman.  This is less than the full capacity of the lungs, as it is not possible to completely evacuate them.  Nevertheless, it is considerably more than we use in everyday life, which means that a lot of the air in our lungs is not exchanged with normal breathing.  Deep breathing, either induced by exercise or through deliberate techniques such as are found in yoga, is an excellent way to flush stale air out of the lungs and replace it with fresh.

When we make ourselves pant with exercise, we are creating an oxygen debt in our bodies, and this, in turn, is tells the body that it needs to increase it's capacity for absorbing and distributing oxygen, our aerobic capacity.  We grow more alveoli in our lungs, increasing the capacity to take in air, and new capillaries in our muscles better to distribute the oxygen to them and carry away carbon dioxide.  If we overdo it and cannot supply enough oxygen for a sustained period, the body switches to less efficient anaerobic respiration, producing lactic acid as a by product, which makes us feel stiff and sore afterwards.

So the occasional whooping for air is a good thing.  It clears out the stale air in our lungs, and contributes to making us fitter.