'Strength training for breathing muscles' holds promise for host of health benefits
University of Colorado at Boulder
Working
out just five minutes daily via a practice described as "strength training
for your breathing muscles" lowers blood pressure and improves some
measures of vascular health as well as, or even more than, aerobic exercise or
medication, new CU Boulder research shows.
The study,
published June 29 in the Journal of the American Heart Association, provides
the strongest evidence yet that the ultra-time-efficient maneuver known as
High-Resistance Inspiratory Muscle Strength Training (IMST) could play a key
role in helping aging adults fend off cardiovascular disease -- the nation's
leading killer.
In the United
States alone, 65% of adults over age 50 have above-normal blood pressure --
putting them at greater risk of heart attack or stroke. Yet fewer than 40% meet
recommended aerobic exercise guidelines.
"There are a lot of lifestyle strategies that we know can help people maintain cardiovascular health as they age. But the reality is, they take a lot of time and effort and can be expensive and hard for some people to access," said lead author Daniel Craighead, an assistant research professor in the Department of Integrative Physiology. "IMST can be done in five minutes in your own home while you watch TV."
Developed in the
1980s as a way to help critically ill respiratory disease patients strengthen
their diaphragm and other inspiratory (breathing) muscles, IMST involves
inhaling vigorously through a hand-held device which provides resistance.
Imagine sucking hard through a tube that sucks back.
Initially, when
prescribing it for breathing disorders, doctors recommended a 30-minute-per-day
regimen at low resistance. But in recent years, Craighead and colleagues have
been testing whether a more time-efficient protocol -- 30 inhalations per day
at high resistance, six days per week -- could also reap cardiovascular,
cognitive and sports performance improvements.
For the new
study, they recruited 36 otherwise healthy adults ages 50 to 79 with above
normal systolic blood pressure (120 millimeters of mercury or higher). Half did
High-Resistance IMST for six weeks and half did a placebo protocol in which the
resistance was much lower.
After six weeks,
the IMST group saw their systolic blood pressure (the top number) dip nine
points on average, a reduction which generally exceeds that achieved by walking
30 minutes a day five days a week. That decline is also equal to the effects of
some blood pressure-lowering drug regimens.
Even six weeks
after they quit doing IMST, the IMST group maintained most of that improvement.
"We found
that not only is it more time-efficient than traditional exercise programs, the
benefits may be longer lasting," Craighead said.
The treatment
group also saw a 45% improvement in vascular endothelial function, or the
ability for arteries to expand upon stimulation, and a significant increase in
levels of nitric oxide, a molecule key for dilating arteries and preventing
plaque buildup. Nitric oxide levels naturally decline with age.
Markers of
inflammation and oxidative stress, which can also boost heart attack risk, were
significantly lower after people did IMST.
And, remarkably,
those in the IMST group completed 95% of the sessions.
"We have
identified a novel form of therapy that lowers blood pressure without giving
people pharmacological compounds and with much higher adherence than aerobic
exercise," said senior author Doug Seals, a Distinguished Professor of
Integrative Physiology. "That's noteworthy."
The practice may
be particularly helpful for postmenopausal women.
In previous
research, Seals' lab showed that postmenopausal women who are not taking
supplemental estrogen don't reap as much benefit from aerobic exercise programs
as men do when it comes to vascular endothelial function. IMST, the new study
showed, improved it just as much in these women as in men.
"If aerobic
exercise won't improve this key measure of cardiovascular health for postmenopausal
women, they need another lifestyle intervention that will," said
Craighead. "This could be it."
Preliminary
results suggest MST also improved some measures of brain function and physical
fitness. And previous studies from other researchers have shown it can be
useful for improving sports performance.
"If you're
running a marathon, your respiratory muscles get tired and begin to steal blood
from your skeletal muscles," said Craighead, who uses IMST in his own
marathon training. "The idea is that if you build up endurance of those
respiratory muscles, that won't happen and your legs won't get as
fatigued."
Seals said
they're uncertain exactly how a maneuver to strengthen breathing muscles ends
up lowering blood pressure, but they suspect it prompts the cells lining blood
vessels to produce more nitric oxide, enabling them to relax.
The National
Institutes of Health recently awarded Seals $4 million to launch a larger
follow-up study of about 100 people, comparing a 12-week IMST protocol
head-to-head with an aerobic exercise program.
Meanwhile, the
research group is developing a smartphone app to enable people to do the
protocol at home using already commercially available devices.
Those
considering IMST should consult with their doctor first. But thus far, IMST has
proven remarkably safe, they said.
"It's easy
to do, it doesn't take long, and we think it has a lot of potential to help a
lot of people," said Craighead.
