One recent visitor to a local swim class was asking how he could improve his lung capacity. He said he has quit smoking not too long ago and was wanting to learn methods to train his lungs to hold more air, longer.
What a swimmer experiences when they run out of air is hypoxic pain. This is the burning urgency experienced in the lungs which create an urgent need to draw in a breath.
What the gather of swimmers had to say seemed to be a lot of good advice, which the man was eager to take.
First, he was advised to try swimming sets and increasing the number of strokes between breaths with each set. The way it would work is he would swim one 50 meter length of the pool taking a breath every third stroke of his arms. He could do this about ten times, and then increase the number of strokes between breaths to four. He could repeat this interval until he was swimming seven strokes between breaths, and then gradually repeat the process in reverse.
Another workout actually consisted of standing in one place in the pool. He would take in a deep breath and then submerge. While under water he would slowly and deliberately expel all the air from his lungs. Once he was deprived of air he would resist the urge to emerge from the water and take a breath for as long as possible.
Once the hypoxic pain was too much he would raise up from the water and take in a deep breath, again repeating the process. The real goal of these exercises is not actually to stretch out the lungs. It is in reality to train the lungs to become more efficient at drawing air out of each breath faster. Swimming, overall, should help with lung capacity and efficiency.
