How Revving Up Your Heart Rate, Even A Bit, Pays Off
Runners take the jogging path around the Central Park reservoir - A new study of 13,535 women finds that brisk walkers — who moved at a clip of about 3 mph — were 90 percent more likely to be free of diabetes and kidney disease. (Stan Honda / AFP/Getty Images)
There's solid evidence that aerobic fitness ups the odds of living longer. Research suggests that just 30 minutes a day, five days a week can keep you fit. The question is: How do you know you're getting enough out of your 30-minute workout? That's where your heart rate comes in.
Reaching your target heart rate — which is calculated based on your age, gender and resting heart rate — allows you to burn off calories without putting yourself at risk of an injury. And raising your heart rate isn't as hard as you might think.
The minute we roll out of bed in the morning, our hearts begin to respond.
(Allison Aubrey / NPR)
"As we start to move, the muscles call on the heart to deliver oxygen," explains Bob Karch, an exercise researcher at American University. As this happens, the heart rate increases.
Karch straps on a heart-rate monitor and shows how quickly the heartbeat moves into a target zone for cardiovascular fitness:
"I've been racing around all morning from meeting to meeting," Karch says. And he's had a few cups of coffee, which can speed up the beat, too. The monitor shows his pulse is already elevated from its resting rate in the high 60s.
(Mario Tama / Getty Images)
"I'm in the mid-80s just standing here talking," Karch says. At 86 beats per minute, his heart is working a little harder to pump blood and oxygen to his muscles. As he climbs a flight of stairs to get to the third-floor classroom, his heart rate nearly reaches 100 beats a minute.
For Karch, a fit man in his 60s, 100 beats puts him at the low end of the target heart rate zone. (Calculate your resting and exercise target heart rate ranges by typing your age and gender into the top of this Web page). Exercise in this range typically lessens the risk of injury and increases the likelihood of fat-burning — especially if you keep it up long enough.
Karch has been training for decades, so he's able to charge up a few more flights of stairs. And his heart rate stays near the 60 percent range of maximum effort. It's generally not recommended to exercise above 85 percent of your maximum heart rate.
As we begin to build up aerobic fitness, our body moves oxygen and blood into our muscles more efficiently, Karch says.
"And we increase the efficiency of the muscles in actually utilizing the oxygen." The result is that, over time, we can move more with less effort.
"It doesn't take a lot to move from a sedentary behavior to where we're getting a training effect," Karch says.
For folks who are deconditioned — meaning, not in the habit of exercising at all — as little as 72 minutes a week can improve fitness. And a pace of 20 minutes per mile (3 miles per hour) is enough.
"I like to tell people that if I were to take you on a walk at this pace, you'd probably say, 'This isn't exercise!' " says researcher Tim Church of the Pennington Biomedical Research Center.
Church's research has pinned down the specific benefits of exercise at this pace. The women in his study — who were in their 50s or older — walked on a treadmill several times a week for a total of 72 minutes. Church says he expected the 72-minute-per-week group to merely maintain their current fitness level. But during six months of treadmill walking, the women's cardiovascular fitness improved.
"To see an almost 4 percent increase in fitness was really surprising to me," Church says.
Brisk Walking Key To Thriving Later In Life
And the evidence gets stronger. A new study of 13,535 women finds that women who regularly walked for exercise in their 50s were much healthier in their 70s and beyond.
"This is the big picture," says epidemiologist Francine Grodstein of the Brigham and Women's Hospital. "This wasn't just looking at who had a heart attack." The researchers looked to see whether women had developed chronic conditions, including diabetes, kidney disease, Parkinson's disease and pulmonary disease. They also looked at cognitive function.
What they found might be surprising, given the level of exercise involved. The brisk walkers — who moved at a clip of about 3 mph — were 90 percent more likely to be free of all these conditions when compared with women who weren't in the habit of walking beyond a leisurely pace.
Benefits Beyond The Heart
Nowadays, much of the focus on fitness is about how to exercise to prevent obesity. One school started measuring target heart rate zones as part of an in-school exercise program. And they found it helped more than just the students' physical health.
"[Exercise] should be fun," says principal Craig Rupert of Woodland Elementary School in Kansas, Mo., as he shows off his school's gym, which has been converted into an exercise arcade.
With the help of the national nonprofit group PE4Life, he's pushing to expand physical education. Rupert says by sixth grade, the majority of students do not participate in organized, competitive athletics; their level of activity starts to drop off. The PE4Life model encourages exercise as a form of play.
"It's really about getting the kids to exercise every day," Rupert says.
On a rainy, cold Wednesday afternoon, Rupert shows how his eighth-graders are getting their heart rates up. Student Juan Reynoso cycles through a video racing game called Off-Road.
"The bike is connected to a remote control," Juan explains. "And when I pedal, it makes the car go."
As physical education instructor Bernie Fitzpatrick makes the rounds, she takes a look at Juan's heart rate monitor. Juan and his classmate Kevin Thompson have hit their target zones at about 140 beats per minute. "Keep it up," she says.
"I feel great," says Kevin, as he moves from cycling to a dance game. "And energetic."
Fitzpatrick says the point of wearing the heart-rate monitors is to teach the kids what it feels like to be exercising at the proper pace — about 60 percent of their maximum.
"If you're in the target heart rate zone, you're burning more of the fat you have stored." When people exercise beyond 80 percent of max, the body starts to burn more sugar. "So by keeping them in that, we get them to be more lean and to use up some of that body fat rather than just the candy bar they ate a little while ago."
And, Fitzpatrick says, at Woodland, the students exercise far more frequently than the 50 minutes a week of physical education typical at many schools.
No one has tested the kids at Woodland Elementary to see if the daily exercise has led to specific improvements in academic success, but PE4Life has begun to document academic gains.
The big surprise for administrators at Woodland Elementary: They've noted a significant decrease in aggressive behavior. In-school suspensions have gone down about 60 percent since the program began.
"I've seen that go down quite a bit, because they can expend that energy on the exercise equipment," says Mark Dickerson, who oversees discipline referrals.
"I've always exercised to blow off steam," Dickerson says. But the transformation at the school has surprised him. "I didn't make the connection ... that it can happen to kids, as well."
Brain Changes
Changes in the brain during exercise could help explain the students' improved behavior. There's increased blood flow to the prefrontal cortex during and just after exercise:
"They're activating this prefrontal area," says John Ratey, a clinical professor of psychiatry at Harvard Medical School. "One of the jobs [of this part of the brain] is to inhibit the impulsivity coming up from the emotional part of the brain."
This means kids may be more likely to think before they act.
Research in adults has shown exercise can boost blood flow, which can lead to improved focus and attention — not to mention a mood lift. Ratey says researchers are just beginning to nail down the benefits in children.
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RENEE MONTAGNE, host:
This is MORNING EDITION from NPR News. Im Renee Montagne.
STEVE INSKEEP, host:
And Im Steve Inskeep. Good morning. Today in Your Health on this Monday morning, NPRs Allison Aubrey continues her series on small changes that can make a big difference. And today, were going to talk about the power, Allison, of revving up your heart rate. I suppose thats why were in the basement of the NPR headquarters here, right?
ALLISON AUBREY: Oh, and youve never been down here, to the workout room?
INSKEEP: Hardly ever. And calling it a workout room is a stretch. It looks like a storage room with a bunch of junk in it. But, OK. Anyway.
AUBREY: But there is a treadmill here. I checked it out, and it works. I have also gotten your pulse this morning: 80 beats per minute.
INSKEEP: OK.
AUBREY: What I want you to do is hop on this treadmill here.
INSKEEP: No trouble. No trouble.
AUBREY: Were going to get going at about a three-mile-per-hour pace.
INSKEEP: This is all very unfamiliar technology. OK. Here we go. Ive hit the start button.
AUBREY: The point here is to illustrate how much - or really, how little it takes to get your heart into the range where theres a benefit.
INSKEEP: OK. Were beginning to do kind of a brisk walk. You know, were not running here, but were going OK.
AUBREY: All right. We just moved you up to a three-mile-per-hour pace. You know, people really tend to underestimate the power of a walk, but were going to show you what would happen if you treadmilled your way through this D segment of MORNING EDITION every morning.
INSKEEP: So Im just walking briskly for eight or nine minutes here, which is the length of this segment of the program. Cant wait.
AUBREY: OK, Steve. You keep walking, and Im going to explain exactly what happens as your heart starts to rev up a bit.
To understand this, let me introduce you to Bob Karch. Hes an exercise researcher, and I met up with him a few days ago on the campus of American University, where he teaches. And he put a heart rate monitor on for us.
Professor BOB KARCH (Exercise Researcher, American University): I've been racing all morning - literally, racing all morning from meeting to meeting. So Ive been pretty active, if you will.
AUBREY: So what is your reading right now?
Prof. KARCH: Right now, Im actually about in the mid-80s right now, just standing here talking.
AUBREY: The monitor reads 86 beats per minute, to be precise, which is 15 or 20 beats faster than his resting heart rate when he rolls out of bed in the morning. All the rushing around, combined with a few cups of coffee, means his heart is responding. Its working a little harder to pump blood and with it, oxygen to his muscles, where theyre needed.
Prof. KARCH: Were in the Ward Circle building. Well go down here.
AUBREY: Karch heads up to a classroom on the third floor. Instead of pushing the elevator button, he hits the stairs.
Prof. KARCH: Were up to about - almost 100.
AUBREY: One hundred beats per minute puts Karch into the low end of the target heart rate zone for his age group. So theres benefit here, especially if he keeps it up.
Prof. KARCH: And as we start to move, as those muscles move, they use oxygen to liberate the energy.
AUBREY: And the more we do this, the fitter the heart becomes, the more readily oxygen is supplied and the more efficient our muscles become in using it. The whole point here is that aerobic fitness means we move more with less effort. Karch races up a few more flights, towards the mechanical room, to make a point.
Prof. KARCH:�There we go. We got it up to 117. Thats pretty good.
AUBREY: Karch says at this range, which is right in the middle of his target heart rate zone, we can get a good workout.
Prof. KARCH: It doesnt take a lot to move from that sedentary behavior to where were getting a training effect.
AUBREY: Actually, back to you, Steve. Now, youve been on this treadmill about four minutes. I know youre in good shape, but how you feeling here?
INSKEEP: No, I feel good. I feel good.
Dr. TIM CHURCH (Pennington Biomedical Research Center): Yeah, I like to tell people that if I were to take you on a walk at this pace, you'd look at me and say this probably isnt exercise.
AUBREY: Thats researcher Tim Church of the Pennington Biomedical Research Center. Its his research that has pinned down the specific benefits of moderate exercise. The women in his study - who were in their 50s and older -walked on treadmills for a total of 72 minutes a week. Their pace was about a 20-minute mile.
Dr. CHURCH: I expected a 72-minute-per-week group to kind of hold serve, because, you know, as you age you lose 1 to 2 percent of fitness a year.
AUBREY: But this is not what he found. During six months of treadmill walking, the women's cardiovascular fitness improved.
Dr. CHURCH: To see almost a 4 percent increase in fitness was really surprising to me.
AUBREY: So Steve, Im going to check in with you again. You know, the most important message here is that the benefits dont end with just aerobic fitness.
INSKEEP: What other benefits are there?
AUBREY: Theres pretty good evidence that aerobic fitness is a key predictor of not only longevity, but successful aging. This huge, new study of some 13,000 women finds that those who are in the habit of walking for exercise at a pace like this, about five days a week for half an hour when theyre in their 50s, that theyre much, much more likely to cross into their 70s disease-free.
The researchers came up with a sort of big-picture composite of successful aging. They looked at whether the women had developed diabetes, heart disease, or any of the other major chronic diseases, and how their mental fitness had held up.
What they found is that these moderately brisk walkers were about 90 percent more likely to be free of these diseases, and mentally fit at age 70, compared to the folks who didn't walk for exercise. So the benefits are really pretty striking.
INSKEEP: You mentioned a benefit to the brain. Im not sure Im feeling that immediately. Whats the benefit to the brain?
AUBREY: Well, to answer this question, Im going to take you to a school I visited in Kansas City, Missouri: Woodland Elementary, where every kid gets into their target heart rate zone for at least 20 minutes a day - at least, thats the goal.
Unidentified Man: Lets go. Two more for everyone.
AUBREY: As the fourth graders swim backstroke laps, the eight graders work out in a tricked-out exercise arcade.
Student Juan Reynoso cycles through a video racing game called Off-Road.
Mr. JUAN REYNOSO: The bike is connected to a remote control and when I pedal, it makes the car go.
AUBREY: Instructor Bernie Fitzpatrick makes the rounds. She's checking kid's heart rate monitors to see if they're in the zone.
Ms. BERNIE FITZPATRICK (Physical Education Instructor, Woodland Elementary): Nice job.
AUBREY: Reynoso and his classmate Kevin Thompson are right where they need to be, in their target zone for 13- and 14-year-olds - at about 140 beats per minute.
Ms. FITZPATRICK: So how do you feel?
Mr. KEVIN THOMPSON: I feel great. And energetic.
AUBREY: Fitzpatrick says she doesnt expect them to wear these monitors when they exercise all the time, but the point in doing it here is to teach them what it feels like to be exercising at this pace, at about 60 percent of their max.
Ms. FITZPATRICK: If you are in the target heart rate zone, you're burning more of the fat that you have stored. So by keeping them in that, we get them to be more lean, and to use up some of that body fat rather than just the candy bar they ate a little while ago.
AUBREY: And so how is this good for the brain? Well, Harvard scientist John Ratey explains at this intensity, the front part of the kid's brains, the prefrontal cortex, gets a boost of oxygenated blood.
Dr. JOHN RATEY (Psychiatry, Harvard Medical School): First, there's more activity in that area, and with more blood flow then there's better attention and focus.
AUBREY: No one has tested the kids at Woodland to see if these correlations are significant enough to make a difference in their grades. But what administrators have seen is a big drop in aggressive behavior, with in-school suspensions down about 60 percent.
Mark Dickerson oversees discipline referrals.
Mr. MARK DICKERSON (Principal, Woodland Elementary): And I've seen that go down quite a bit because they can expend that energy on the exercise equipment.
AUBREY: Dickerson says as an adult, he's always used workouts to blow off stream. But it wasnt until his school started the daily PE that he noticed it with kids.
Mr. DICKERSON: I didnt make the connection until it was actually happening, and then it was like wow, oh, yeah. It can happen to kids as well.
AUBREY: What's happening in these kid's brains just after exercise may help explain this improvement. Here's John Ratey again.
Dr. RATEY: And it's probably because they're activating this prefrontal area, which - one of the jobs that it has is to inhibit the impulsivity coming up from the emotional part of the brain.
AUBREY: Making it easier to think before acting. Ratey says the benefits of exercise on brain function, which are well-documented in adults, are just starting to be nailed down in children.
OK, Steve, it's been about eight minutes now. Let's check your pulse here.
INSKEEP: Well, I picked up the pace. I'm going about four miles an hour, and it's getting up around 115 to 120 beats per minute.
AUBREY: You are in that target heart rate zone.
INSKEEP: Now, I realize that this is good for me, generally speaking, to be going here four miles an hour. But didnt we already kind of know that, that that generally is helpful to you?
AUBREY: Well, the value of all of this research is that it gives us more prescriptive information. So think of exercise as a drug. Knowing the benefits of different levels of fitness and endurance gives us that same precision.
And stepping back a bit, you know, about 30 percent of health-care spending is related to the treatment of chronic diseases - the lifestyle-related diseases that in many cases, are preventable or more manageable. So given this toll, given the billions of dollars being spent, it's really not a surprise that there's so much focus on measuring the benefits of exercise.
INSKEEP: Well, Allison Aubrey, its been great talking with you, but I think I'm going to go for a run.
AUBREY: Actually, you can put your work shoes back on.
(Soundbite of music)
INSKEEP: It's MORNING EDITION from NPR News. Transcript provided by NPR, Copyright National Public Radio.
