Muscles of Breathing and the Lungs

As people age, the muscles used in breathing, such as the diaphragm, tend to weaken. Also, slightly less oxygen is absorbed from air that is breathed in. In people who do not smoke or have a lung disorder, the muscles of breathing and the lungs continue to function well enough to meet the needs of the body during ordinary daily activities. But these changes may make exercising vigorously (for example, running or biking energetically) more difficult. Older people may also have more difficulty breathing at high altitudes.

The lungs become less able to fight infection, in part because the cells that sweep debris out of the airways are less able to do so. Cough, which also helps clear the lungs, tends to be weaker.