April 9 (HealthDay News) -- A person who maintains aerobic fitness may delay biological aging by up to 12 years, a new analysis shows.

Jogging and other types of aerobic exercise improve the body's oxygen consumption and its use in generating energy (metabolism). However, a steady decline in maximal aerobic power begins in middle age, decreasing about 5 ml/ (kg. min) every decade, according to the information in the analysis.

When maximal aerobic power falls below about 18 ml in men and 15 ml in women, it becomes difficult to do any activity without experiencing major fatigue. A typical 60-year-old sedentary man has a maximal aerobic power of about 25 ml, nearly half of what it was at age 20.

But research shows that a long period of relatively high-intensity aerobic exercise can increase maximal aerobic power by 25 percent (about 6 ml), which equals 10 to 12 biological years.

The analysis was published online in the British Journal of Sports Medicine.

"There seems good evidence that the conservation of maximal oxygen intake increases the likelihood that the healthy elderly person will retain functional independence," said study author Dr. Roy Shephard, of the Faculty of Physical Education and Health and Department of Public Health Sciences, at the University of Toronto in Canada.

Aerobic exercise also reduces the risk of serious disease and promotes faster recovery after injury or illness. Additionally, it helps maintain muscle power, balance and coordination, which reduces the risk of falls.

SOURCE: BMJ Specialist Journals, news release, April 10, 2008