July 25, 2005 -- Our fitness levels naturally begin a slow decline after our 20s and plummet once we reach our 70s, according to a new study.
But the good news is that regular exercise may compensate for some of those natural losses and help your body feel years younger.
Researchers measured the decline in maximum exercise capacity -- as measured by VO2 max, which measures the amount of oxygen the body consumes during peak exercise performance. While age per se results in a decrease in maximum exercise capacity, age-related decreases in the amount of muscle and vigorous physical activity also contribute to this decline, write the authors.
As maximum exercise capacity declines, physical activity and fitness levels generally decline as it takes more effort to exercise or walk up a flight of stairs, and a person becomes more easily exhausted.
"This study does not mean that older people can't improve their fitness," says researcher Jerome L. Fleg, MD, a cardiologist at the National Heart, Lung, and Blood Institute in Bethesda, Md., in a news release.
"Over time, your aerobic capacity (exercise capacity) will decline, but at any given age someone who exercises will have a higher capacity than someone who is a couch potato," says Fleg. "By participating in a training program, you can raise your aerobic capacity 15% to 25%, which in our study would be equivalent to being 10-20 years younger."
Aerobic Capacity Drops in Old Age
In the study, researchers followed the change in aerobic capacity in more than 800 men and women aged 21 to 87 over a period of nearly eight years. Researchers calculated the participants' maximum exercise capacity during treadmill tests about every four years.
The results showed that aerobic capacity declined each decade in men and women but at a much greater rate in the older age groups.
For example, aerobic capacity declined 3% to 6% each decade in the 20s and 30s, but after age 70 the rate of decline accelerated to more than 20% per decade.
The study also showed that after age 40, men's fitness levels declined at a faster rate than women, regardless of their level of physical activity.
"These results are even more striking given that we were looking at the best-case scenario," says Fleg. "Participants were required to have no previous heart attack or stroke and to be healthy and agile enough to walk on the treadmill. The rate of decline in the population-at-large is probably somewhat greater than what we observed here, because many older people will have disease-related deficits in addition to those brought on by age."
The accelerated rate has substantial implications with regard to functional independence and quality of life, not only in healthy older persons, but particularly when disease-related deficits are superimposed, they write.
Given the importance of aerobic capacity in activities of daily living, efforts to increase and maintain higher levels of VO2 max, in addition to strength training, in older adults would likely improve their ability to live independently with a higher quality of life, they conclude.