Fitness in Less Time Than You Think
As Little as 72 Weekly Minutes of Moderate Exercise May Help
WebMD News Archive
May 15, 2007 -- Short on time for exercise? Getting fitter may not put as
much of a dent in your schedule as you think.
A new study shows that it may take as little as 72 minutes of moderate
exercise per week to improve aerobic fitness.
That's nearly half the minimum amount of moderate exercise recommended by
the CDC and other health organizations.
When it comes to exercise, the rule of thumb appears to be that "even a
little is good; more may be better!" exclaims an editorial published with
the new study in The Journal of the American Medical Association.
The new study included 464 sedentary, overweight, postmenopausal women
with elevated blood pressure
who were 57 years old, on average.
First, the women tested their aerobic fitness on a stationary bike, pedaling
as hard as they could while cranking up the resistance on the bike.
Next, the researchers -- who included Louisiana State University's Timothy
Church, MD, PhD, MPH -- randomly split the women into four groups.
Three of the four groups were assigned to get moderate-intensity exercise on
a stationary bike or treadmill three or four times per week for six months.
Those three groups varied in their amount of prescribed weekly exercise. One
group exercised for 72 minutes per week. Another group worked out for
136 minutes per week. The third group worked out for 192 minutes per
For comparison, women in the fourth group weren't assigned to exercise.
Assigned workouts were done under expert supervision. That way, the
researchers made sure that the women followed their exercise assignments.
The women also got up to $350 in financial incentives to stick with the
study. They got less money if they missed a week of workouts. Most women saw
the study through to the end.
At the end of the six-month study, the women repeated the fitness test. The
results show that all of the exercise groups had boosted their aerobic
Compared with the no-exercise group, average scores on the fitness test
improved by 4% for the women who worked out for 72 minutes per week, by 6% for
women who worked out for 136 minutes per week, and 8% for women who worked out
for 192 minutes per week.
Those results take other factors into consideration, including age, BMI,
race, and hormone therapy.
The women's weight didn't change, but the study wasn't designed for weight
loss and didn’t require dieting or changing eating habits.
Blood pressure also didn't change during the study, except for a slight drop
in blood pressure in the women who got the most exercise. Weight loss or more
intense exercise might have been more beneficial to the women's blood pressure,
Church's team notes.