March 16, 2006

Drop in exercise efficiency with age can be eased

By Amy Norton

NEW YORK (Reuters Health) - Older adults may have to work
harder than young people to perform the same physical activity,
but regular exercise may close that age gap, research findings

In a study comparing sedentary adults in their 60s and 70s
with those in their 20s and 30s, researchers found that older
men and women had to use much more oxygen to walk at the same
speed as their younger counterparts.

But that was before they went through a six-month exercise
program. After taking up walking or jogging, biking and
stretching, the senior study participants reversed their loss
of exercise "efficiency."

Exercise efficiency refers to how much energy the body
expends to perform a given activity. At the start of this
study, older men and women used 20 percent more oxygen to walk
at the same speed as a younger person, said Dr. Wayne C. Levy
of the University of Washington in Seattle, the study's senior

But six months of regular exercise -- 90 minutes, three
days per week -- improved older participants' exercise
efficiency by 30 percent, versus only 2 percent among their
younger counterparts.

The findings are published in the current issue of the
Journal of the American College of Cardiology.

It's well known that as people age, there is a decline in
exercise capacity -- how much work a person can do before
becoming exhausted. But the new findings suggest this is not
just a product of the aging cardiovascular system being less
able to send oxygen to working muscles. The older body also
needs more oxygen to perform the same work as a younger one --
that is, exercise efficiency declines.

But this decline appears to arise largely from inactivity,
and may well be reversible.

The idea that exercise efficiency dips with age is a
"relatively new concept," Levy told Reuters Health. And though
younger people in his study were still better at pumping blood
and oxygen to their muscles after exercise training, it was
only the older exercisers who showed significant gains in
exercise efficiency.

Their "disproportionately" greater improvement in this
area, Levy and his colleagues write, is "new and unexpected."

It's not clear yet how intensely people need to exercise to
hang on to their efficiency as they age, according to Levy. But
he said he suspects that any activity done regularly, including
walking, would have benefits.

SOURCE: Journal of the American College of Cardiology,
March 7, 2006.