Octogenarians who spend a lifetime doing endurance exercise have the aerobic capacity of 40-year-olds.
For their age, these ultra-athletes have the highest aerobic capacity ever measured, suggesting that lifetime endurance training may ward off age-related declines in fitness.
The findings also strike a more hopeful note than past work, which found that starting an exercise regimen in old age didn't do much to boost aerobic capacity.
"These individuals' aerobic power was about 80 percent higher than the typical 80-year-old, and it was comparable to people forty and fifty years younger," said lead author Scott Trappe, an exercise researcher at Ball State University.
The nine elite, life-long cross-country skiers from Northern Sweden who participated in the study had dabbled in orienteering, running and cycling, but their primary passion was the snow sport, Trappe told LiveScience. The study included only male athletes. [7 Amazing Superhuman Feats]
In the experiment, the octogenarians rode exercise bikes that started out at slow speeds, but ramped up until the riders were too exhausted to keep going. All the while, the research team measured how much oxygen the athletes were using. (Researchers also monitored the riders for changes in the heart's electrical activity and blood pressure to make sure the exercisers were not in distress.) The point of exhaustion marked the riders' maximum oxygen capacity, or VO2 max.
The team also took pea-size muscle biopsies to measure the capacity of the mitochondria, the aerobic powerhouse of the muscle and other cells.
When compared with six healthy, sharp, but untrained Indiana octogenarians, the athletes had a VO2 max 80 percent higher, similar to that of men decades younger. VO2 max is a powerful predictor of heart attack risk, even more so than traditional risk factors like cholesterol, Trappe said.
Of course, the men weren't exactly slouches. All had been superb athletes when younger, including a 91-year-old who was once an Olympic cross-country ski champion.
"They had the right stuff to begin with," Trappe said.
Still, the key was not the athletes' youthful elite level of exercise, but the fact that they kept it up, he said. "It's kind of a use-it-or-lose it type phenomenon," Trappe said.
In fact, some research has shown that elite athletes who give up their sport in older age suffer worse consequences than non-competitors. Marathon runners who retire to the couch show a steeper decline in oxygen capacity than people who have never exercised regularly.
The octogenarian findings suggest that even those with less athletic prowess can stay fit and healthy into old age, said Michael Joyner, an exercise researcher at the Mayo Clinic who was not involved in the study.
For mere mortals, doing a half-hour to an hour of vigorous exercise most days should keep aerobic capacity high enough to allow longer life and the ability to live independently well into the 80s, he added.
"This long decline into disability, it's not our biological destiny," he said.
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