Interval Training: Good Exercise For All Ages
Kristine Oleson (John Poole / NPR)
The fitness boot camp craze is evolving. It's no longer just the crack-of-dawn, sergeant-led calisthenics classes.
Mommy Bootie Camp in Kensington, Md., packs a lot of punch, with a focus on interval training.
Moms meet three times a week at a local synagogue — and many of them bring their kids along. "They have a built-in play date while we exercise," says instructor Kristine Oleson.
To maximize the hour-long class, Oleson incorporates a lot of short bursts of high-impact cardio. There's skipping, jumping rope and running in place.
"Pick up your intensity," Oleson calls out to her class of about 30 moms as they move through a round of skipping. "Really push it!"
The goal is to get heart rates up to about 85 percent of maximum for short clips of time, and then dial back down to a slow or moderate pace.
"The benefit of interval training is that it's a very efficient way to increase your fitness quickly," says researcher Tim Church of the Pennington Biomedical Research Center.
Church says intervals aren't just for athletes and fit moms. Increasingly there's interest in building them into the routines of older folks and those with chronic conditions such as diabetes or heart disease.
"This is really a hot area of research," Church says. Preliminary studies suggest there's an additional benefit — beyond the benefits of steady-paced exercise — to mixing in some interval training.
Interval Training For The Middle-Aged And Slightly Plump
Researchers in Australia have tried to find the most effective pacing for interval training. They're focused on bringing the approach to folks who are pudgy around the middle and older than 40.
"Everybody can do 8-second sprints," says Steve Boutcher, a professor of exercise science at the University of New South Wales.
His studies have documented the benefits of 20-minute workouts on stationary bikes. Participants cycled three times per week. They alternated between 12 seconds of slow, gentle peddling and 8-second intense sprints, peddling as hard as they could.
"In the 20-minute bout," Boutcher says, the actual hard exercise totaled just 8 minutes, "so it's not that much exercise." But the payoff was significant.
Over the course of four months, participants lost an average of 6 pounds of body fat. By comparison, those who cycled at a steady pace for 40 minutes, without mixing in the interval sprints, lost less than 2 pounds.
(John Poole / NPR)
Researchers are not certain how to explain this difference. But Boutcher is studying the role of chemical compounds called catecholamines.
Boutcher says our bodies seem to produce higher levels of catecholamines during sprint-type exercises that elevate the heart rate.
"These are hormones that tell the fat cells to release their fat," Boutcher explains.
Don't Want To Cycle? There Are Alternatives
If cycling doesn't interest you, Boutcher's advice is to try swimming, rowing or stair-climbing. If you like to walk, throw in some hills at a faster clip — anything to mix up the pace.
But it's also important to recognize your limits, and to start out slowly.
"I'm a huge supporter of interval training because I think the payoffs are great," Church says. "I mix them into my workouts on a weekly basis." But he cautions that people need to be careful.
"We see men who are 45, and they've been sitting at a desk for the last 15 years, and they want to start doing their high school football workouts again," Church says. They don't realize how out of shape they may be. Church advises people to check in with their physicians before starting any intense interval training, especially those who are managing a chronic condition.
Seeing Results At Mommy Bootie Camp
After years of running, mostly at a steady pace, the interval approach emphasized at Mommy Bootie Camp is paying off for one regular in the class.
"I think it increases stamina, and it does seem to help with weight loss," says Kathleen Sylvester, who brings her two preschool-age children with her to class.
She says interval training has also helped her build long, lean muscles. One other reason she keeps coming: The baby-sitting is built-in.
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STEVE INSKEEP, host:
It's MORNING EDITION from NPR News. I'm Steve Inskeep.
RENEE MONTAGNE, host:
And I'm Renee Montagne. Good morning. In Your Health today, the science behind two different fitness strategies. We'll examine how elementary school kids can benefit from weight-lifting workouts. First, interval training. Athletes have done it for decades. Now, it's all the rage at fitness boot camps. NPR's Allison Aubrey reports on the latest research linking short, intense cardio sprints to weight loss.
ALLISON AUBREY: If you're out of the loop on the whole boot camp craze, it's basically just group fitness classes aimed at whipping people into shape. They're often held outdoors and at the crack of dawn. Much of this appeals to Kristine Oleson. But she decided to start her own mommy boot camp, she swapped a 5 a.m. start time for 10, rented a space in her neighborhood, and opened the doors to moms with their kids in tow. This way, moms wouldn't need to find a babysitter.
Ms. KRISTINE OLESON (Owner, Mommy Bootie Camp): No excuse. No nursery. No money. Bring the kids, and they play. And they have a built-in play date while we exercise.
AUBREY: The kids are sprawled all over the place. Some sit with coloring books and crayons. Others try to keep up with their moms. To maximize the impact of the exercise for the moms, Oleson incorporates lots of short bursts of high-impact cardio. They are skipping, jumping, and running in place.
Ms. OLESON: Pick up your intensity.
(Soundbite of music)
Ms. OLESON: Push. Out, in.
AUBREY: The goal is to get heart rates up to about 85 percent of maximum for just short clips of time, and then dial back down to a slow or moderate pace using the interval approach.
Dr. TIM CHURCH (Pennington Biomedical Research Center): The benefit for interval training is it clearly is a very efficient way to increase your fitness quickly.
AUBREY: Tim Church directs exercise and preventive medicine studies at the Pennington Biomedical Research Center. He says intervals aren't just for athletes and fit moms. Increasingly, there's interest in building them into the routines of older folks and even those with chronic conditions, such as diabetes or heart disease.
Dr. CHURCH: This is really a hot area of research. It is: Is there an additional benefit to mixing in some interval training? And the preliminary work really suggests there is.
AUBREY: So what would interval training look like for, say, middle-aged folks who are overweight? Researcher Steve Boucher of the University of New South Wales in Australia has done several experiments with this age group using 20-minute workouts on stationary bikes. He has participants start with 12 seconds of slow, lackadaisical pedaling, followed by short, eight-second sprints where they pedal as hard as they can. Then they alternate back and forth.
Professor STEVEN BOUTCHER (University of New South Wales): The eight-second sprint is doable by all the groups we've looked at - old people, you know, overweight people. Everybody, so far, we've tested has been able to do it. And in the 20-minute bout, the actual heart exercise is only eight minutes. So it's not actually that much exercise.
AUBREY: But Boutcher says the payoff is impressive. In one four-month study, participants improved both blood pressure and blood sugar readings. In addition, they lost an average of six pounds of body fat. By comparison, those who cycled at a steady pace for 40 minutes, without mixing in the interval sprints, lost three times less fat - not much at all.
Boutcher says he's not certain what explains this difference, but he's focused on certain compounds called catecholamines, which the body seems to produce at higher levels during sprint-type exercises that elevate the heart rate.
Prof. BOUTCHER: Catecholamines is the major chemical that induces fat burning. So these are hormones that really tell the fat cells to release their fat - and for other cells to burn the fat.
AUBREY: If cycling doesn't interest you, Boutcher's advice is to try swimming, rowing or stair-climbing. If you like to walk, throw in some hills at a faster clip — anything to mix up the pace.
One mom who's become a regular at the boot camp, Kathleen Sylvester, says her approach to running used to be, set a steady pace and keep it. But with the interval classes, she's noticed a difference.
Ms. KATHLEEN SYLVESTER: I think it increases your stamina. I think it does help with weight loss. And it also helps develop long, lean muscles.
AUBREY: Which, Sylvester says, pretty much covers it.
Allison Aubrey, NPR News.
MONTAGNE: And you'll find a photo gallery of mommy boot camp at the new npr.org, where you can also sign up for the podcast of Your Health. Transcript provided by NPR, Copyright National Public Radio.
