THURSDAY, Oct. 25(HealthDay News) -- Is lack of time your excuse
for not exercising? New research finds that just a few minutes of
intense activity interspersed between less intense stretches of
exercise will burn excess calories all day long.
Men participating in a small study burned an additional 200
calories a day by doing a workout for less than 25 minutes that
included a few minutes of hard, intense exercise on a stationary
bike, spaced between less intense activity.
The technique, called sprint-interval training, is used by
athletes to improve performance. It seems like a reasonable
strategy for weight maintenance -- and for those days when you just
can't get in a full workout, the researchers said.
"The harder you work, the more calories you will burn per
minute," said study leader Kyle Sevits, a researcher at Colorado
State University in Fort Collins.
Sevits looked at five healthy men of normal weight with an
average age 28. They were asked to ride an exercise bike as hard as
they could five times for 30 seconds each. In between, they did
resistance-free pedaling for four minutes. In all, the workout took
less than 25 minutes.
Sevits compared the men's energy output on two days, including
the day of the cycling exercise. The extra calories were burned
over 24 hours on the workout day, despite the brief time spent in
The findings were presented last week at an exercise conference
in Colorado sponsored by the American Physiological Society, the
American College of Sports Medicine and the Canadian Society for
A British expert finds the results intriguing.
"This study provides some interesting preliminary data showing
that sprint-interval training can increase 24-hour energy
expenditure," said Dr. Stuart Gray, a lecturer in exercise
physiology at the University of Aberdeen in Scotland. Gray was not
involved in the study.
The participants didn't appear to consume more food than normal
or reduce other daily activities to compensate for the bursts of
activity, he said.
However, "this kind of exercise is very intense and may not suit
all," he cautioned. "My advice would be to not simply focus on one
form of exercise but try to increase activity and reduce
consumption wherever and whenever you can."
Still, the sprint technique ''is a useful option if time is a
limiting factor," he said.
Sevits focused on the practical aspects of the research. "Many
people gain a couple of pounds a year," he said, adding that
demanding work schedules and family duties can limit exercise time.
"A time-sensitive exercise that will help them burn some calories
and keep them fit may help ward off those extra couple of
Sevits can't say the technique would work for weight loss, as
that was not studied.
Would another form of exercise burn calories equally well?
"If people do not have access to a gym, they can try to find a
grassy hill," Sevits said. "Sprint as fast as possible up it for 30
seconds, then walk back down."
A treadmill would not work well for sprint-interval training, as
it goes at a constant speed, he said.
Data and conclusions presented at medical meetings should be
considered preliminary until published in a peer-reviewed medical
To learn more about sprint-interval or high-intensity training,
American Council on Exercise.