The lungs work in conjunction with the heart in ridding the body of carbon dioxide and water, and most importantly, in bringing the body oxygenated blood. Every time we take a breath we are supplying the blood, and thence the rest of the body, with oxygen. And we do this thousands of times a day, without even thinking about it.

Until something goes wrong.

One of the things that goes wrong is that we get older. (Although considering the alternative, that's not altogether bad.) As we get older, we have more trouble breathing. Sadly for some, a point is reached where they do think about every breath.

There is a test that is commonly used to tell how well we are able to breathe. It is called the forced expiratory volume test, or FEV1. It measures the volume of air, after filling our lungs fully, that we are able to force out in one second.

Because the FEV1 test correlates so well with age, it is considered to be one of the more reliable indicators in predicting how long a person may expect to live, in the absence of chronic lung disease.

One study done by Cuneo and colleagues looked at how HGH treatment affected exercise capacity. For those who showed a deficiency in HGH levels, an oxygen uptake of only 80% of normal was all they could muster. After HGH therapy, their oxygen uptake had moved into the normal range. Also, their exercise capacity came into the normal range as well, especially for exercise that was carried out at below maximum output.

This meant that they could now perform everyday tasks with normal ease.