By LEE BOWMAN
Scripps Howard News Service
March 08, 2006
Researchers in Seattle found that a thrice-weekly, 90-minute training program done over three to six months made a group of seniors nearly a third more efficient at exercising than they were before training.
"Exercise efficiency" refers to the percentage of energy expended by the body that's converted to actual mechanical output. Exercise capacity is a measurement of how much exercise a person can do before becoming exhausted, as during a treadmill stress test.
"It's well-known that aging is associated with reduced exercise capacity," said Dr. Wayne Levy, a cardiologist at the University of Washington and a co-author of the new study. Researchers looked at people in their mid-60s to late 70s, and used those in their 20s and early 30s as a comparison.
"What is less appreciated is that older subjects have an additional impairment in exercise capacity due to exercise inefficiency. For example, the older subjects used about 20 percent more oxygen to walk at 3.5 miles an hour than the younger subjects. With training, this disparity with aging was abolished."
The study was published Tuesday in the Journal of the American College of Cardiology.
The research found that by one measure of exercise capacity - peak delivery of oxygen to exercising muscle - younger participants had a 42 percent higher capability than the older group. The younger subjects also didn't have to work as hard and were 8 percent more efficient than the older subjects.
Then all participants (34 older men and women, and 27 in the younger group) started a supervised aerobic exercise program. During each workout, they devoted 30 minutes to walking or jogging, 30 minutes to bicycling and 30 minutes to stretching.
After being on the regimen for at least three months, the older subjects were on average 30 percent more efficient at exercising than they were before training, and also had greater peak oxygen delivery.
The younger participants, by contrast, improved their exercise efficiency by only 2 percent, but did benefit from the program by boosting their peak oxygen consumption.
The researchers concluded that given the "disproportionately greater response to training" in the elderly, it appears that much of the decline in exercise efficiency seen with aging may not be inevitable, but rather reflects a lack of fitness that can be addressed by training.
Levy said much more research is needed to understand what level of training seniors might need to sustain exercise efficiency.
"It is unknown the duration, intensity and mode of exercise training necessary to improve efficiency in the older subjects,'' he said. "Will simple walking for two to four weeks be adequate, or is more vigorous exercise necessary?"
Still, the study demonstrated that older people shouldn't automatically lower exercise expectations, said Dr. Joseph Franciosa, a New York cardiovascular specialist and drug-company consultant who was not involved in the study.
"The practical significance of this is that elderly people should not be afraid to exercise, which is good for them. If they are otherwise in good health, they should remain physically active and not slow down just because of age.
"Even if they have medical problems, exercise can still be of considerable value, but this should be undertaken only under a physician's supervision."
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