Telling heart patients to really push themselves during exercise sounds
risky. But a growing body of research suggests that a workout routine athletes
use to get in shape may do the same for some patients.
High-intensity interval training, workouts that consist
of short bursts of intense exercise and rest periods, may be beneficial to
people with heart problems and those at risk for diabetes. Triathlon coach Neil
Cook talks to WSJ’s Christina Tsuei about the method and why he thinks it’s so
effective in improving heart health.
Some scientists and clinics are backing the use of high-intensity interval
training, which involves short spurts of intense exercise at 85% to 95% of
maximum heart rate alternating with periods of moderate exercise. Heart patients
have traditionally built up fitness with steady sessions of aerobic exercise
aimed at keeping the heart beating at about 70% of its maximum rate. That’s
meant to give the heart a workout without risking chest pain or a cardiac event.
Using intense exercise with patients suffering from heart failure and
coronary artery disease, and those recovering from bypass surgery and heart
attacks, is still controversial. Even proponents of the approach say more
research is needed. But studies to date suggest that intense interval training
improves the ability of the body in at least some patients to transport and use
oxygen—which is generally associated with living longer—more effectively than a
steady, moderate workout. The technique is also being studied in people with
hypertension, diabetes and other conditions.
Stephen Maturen for The Wall Street
JournalRoger Solheim, 77, getting back into shape after
double-bypass surgery in April.
Intense interval training is commonly used by athletes to increase their
speed and endurance. Alternating the hard work with periods of more moderate
exercise enables them to accumulate the benefits of an intense workout.
“What our group has done is to train these patients a bit harder,” says Trine
Moholdt, a postdoctoral fellow at the Norwegian University of Science and
Technology. Her team presented a 107-patient study at a scientific meeting last
fall in Stockholm. It showed a cardiac-rehab program that included supervised
high-intensity treadmill workouts improved peak oxygen uptake better than a
standard moderate-intensity program that burned the same number of calories.
Ray Squires, program director of cardiovascular health and rehabilitation at
the Mayo Clinic in Rochester, Minn., has been using high-intensity intervals in
patients for about four years. “There’s been a natural progression over time of
what we’ve thought exercise for patients with cardiovascular disease should be,”
says Dr. Squires. “If you go back 50 years, people were told to hardly do any
exercise for weeks after a heart attack. Gradually we learned that was wrong.”
Stephen Maturen for The Wall Street
Dr. Squires says he believes Mayo is one of the only clinics in the U.S. to
use intense interval training in the early stages of rehab for people who have
recently left the hospital following a heart attack or cardiac surgery. Over
several weeks, patients build up to exercising steadily at a moderate pace for
20 minutes, usually walking on a treadmill. Then they start incorporating
30-second bursts of exercise using faster speeds and a steeper incline at a hard
to very hard pace. “We’ll gradually increase the number of intervals and their
length to 120 seconds,” he says.
The common rule of thumb for determining maximum heart rate people can safely
achieve is 220 minus their age. That guidance isn’t very precise and so, if
their health permits, patients may get a stress test, which monitors the heart
during an increasingly difficult workout. Some doctors instead rely on patients’
perception of their exertion level using a scale of 6 to 20, aiming for as high
as 17, to determine how hard they can go.
Patients’ capacity differs widely. “In heart-failure patients, 90% of max may
be walking,” says Darren Warburton, director of the cardiovascular physiology
and rehabilitation laboratory at the University of British Columbia in
Vancouver, who has researched interval training.
Roger Solheim, a retired schoolteacher in Rochester, Minn., had double-bypass
heart surgery at the Mayo Clinic in April. After three weeks of recovery at
home, Mr. Solheim, 77 years old, began rehab training at the clinic. His initial
fitness level was low, he says. “I couldn’t even go 20 minutes on the treadmill”
with no incline, he says.
After about two weeks of moderate training, Mr. Solheim was instructed to mix
in periods of more intense exercise. Now he goes for 35 minutes, with one minute
of elevated intensity after every five minutes. “Even though [the intense
intervals] are hard, they break up the routine,” he says.
He continues to go to rehab three times a week and hits the gym on his own
about five times a week to lift light weights and do crunches. “I’m getting my
strength back and I’m sleeping a bit better,” he says. He says he is now capable
of mowing the lawn again.
Some patients aren’t good candidates for intense interval training, including
those with recurrent angina or bone or muscle problems.
The American Heart Association doesn’t have a position on high-intensity
interval training for rehab. Barry Franklin, an AHA spokesman, says that
although recent research is encouraging, larger randomized, controlled studies
are needed in higher-risk groups.
“I’m still not convinced … that taking people with coronary disease and
exercising them at 95% of their [maximum] heart rate is a safe procedure,” says
Dr. Franklin, who is director of the cardiac-rehabilitation program and exercise
laboratories at the William Beaumont Hospital in Royal Oak, Mich. Dr. Franklin
says he currently uses intense bursts of exercise only in selected lower-risk
patients, in the later, maintenance phase of rehab.
By contrast, the most recent version of the Canadian guidelines for cardiac
rehab, published in 2009 by the Canadian Association of Cardiac Rehabilitation,
say there is “compelling evidence” that high-intensity interval training can
lead to improvements in aerobic capacity, functional status and quality of life,
and that it can be used as an alternative to traditional continuous
Intense interval training is already being used in some community rehab
centers in Norway, says Dr. Moholdt. She is working to analyze safety data from
those centers and from clinical studies.
Some research also suggests that intense interval training might benefit
people at risk for diabetes. People with insulin resistance “essentially need to
dispose of the glucose” that reaches too-high levels in their blood, says Carl
Foster, a professor in the department of exercise and sport science at the
University of Wisconsin-La Crosse. Increasing the action of the muscle fibers
that fire quickly to generate power needed in intense exercise, known as
fast-twitch muscle fibers, may increase the capacity of the muscles to take up
additional glucose. This is in addition to the capacity of the slow-twitch
fibers used in steady cardio. “If you train twice as many muscle fibers, you’ve
got a place to put it,” says Dr. Foster.
Also, a randomized study of 88 patients with hypertension found that
high-intensity interval training reduced blood pressure more than a steady
workout regimen. The study, by the Norwegian University of Science and
Technology, was published online recently by the European Journal of
Cardiovascular Prevention & Rehabilitation.
High-intensity intervals are “not a panacea,” says Martin Gibala, professor
and chair of kinesiology at McMaster University in Hamilton, Ontario. People
need to be properly screened and supervised, and much bigger studies need to be
done, he says. “But many populations can benefit,” he says.
Adding Intensity to Cardiac Rehab
Interval training has improved some key measures of Mr. Solheim’s fitness.
Some sample data from his workouts.
|Resting heart rate
||84 beats per minute
|Average heart rate
|No. of 1-minute intervals
|Workload during intervals
||2 mph, 0% grade
||2.5 mph, 4% grade
||3 mph, 6% grade
|Workload during recovery
||Same (no intervals)
||2.3 mph, 0% grade
||2.8 mph, 0% grade
|Total workout time
Source: Mayo Clinic