Researchers found significant drops in blood pressure, improvements in large-artery function, and improved performance on certain cognitive and memory tests, by subject who performed Inspiratory Muscle Strength Training, which involves breathing in vigorously through a hand-held device. The preliminary results from the first clinical trails, funded by the US National Institute of Aging, were presented at the Experimental Biology 2019 conference, in Orlando.
IMST was developed in the 1980s as a means to wean critically ill people off ventilators. Imagine sucking hard through a straw which sucks back. There were no changes in test subjects who used a sham breathing device that delivered low-resistance.
"IMST is basically strength-training for the muscles you breathe in with," said Daniel Craighead, a post-doctoral researcher in the University of Colorado Boulder integrative physiology department who is leading the study. "It's something you can do quickly in your home or office, without having to change your clothes, and so far, it looks like it is very beneficial to lower blood pressure and possibly boost cognitive and physical performance."
During early use in patients with lung diseases, patients performed a 30-minute, low-resistance regimen daily to boost their lung capacity. But in 2016, University of Arizona researchers published results from a trial to see if just 30 inhalations per day with greater resistance might help sufferers of obstructive sleep apnoea, who tend to have weak breathing muscles.
In addition to more restful sleep, subjects showed an unexpected side effect after six weeks: Their systolic blood pressure plummeted by 12mm of mercury. That's about twice as much of a decrease as aerobic exercise can yield and more than many medications deliver.
"That's when we got interested," said principal investigator Professor Doug Seals, director of CU Boulder's Integrative Physiology of Aging Laboratory.
Systolic blood pressure, which signifies the pressure in your vessels when your heart beats, naturally creeps up as arteries stiffen with age, leading to damage of blood-starved tissues and higher risk of heart attack, cognitive decline and kidney damage. While 30 minutes per day of aerobic exercise has clearly been shown to lower blood pressure, only about 5% of adults meet that minimum. Meanwhile, 65% of mid-life adults have high systolic blood pressure.
"Our goal is to develop time-efficient, evidence-based interventions that those busy mid-life adults will actually perform," said Seals, who was recently awarded a $450,000 National Institute of Aging grant to fund the clinical trial of IMST involving about 50 middle-aged to older subjects.
Craighead presented preliminary results at Experimental Biology 2019 showing that with about half the tests done, the researchers have found significant drops in blood pressure and improvements in large-artery function among those who performed IMST with no changes in those who used a sham breathing device that delivered low-resistance.
The IMST group is also performing better on certain cognitive and memory tests.
When asked to exercise to exhaustion, they were also able to stay on the treadmill longer and keep their heart rate and oxygen consumption lower during exercise.
Some cyclists and runners have already begun to use commercially-available inspiratory muscle trainers to gain a competitive edge.
But Seals and Craighead stress that their findings are preliminary and curious individuals should ask their doctor before considering IMST.
That said, with a high compliance rate (fewer than 10% of study participants drop out) and no real side-effects, they're optimistic.
"High blood pressure is a major risk factor for cardiovascular disease, which is the number one cause of death in America," said Craighead. "Having another option in the toolbox to help prevent it would be a real victory."
Background: The majority of middle-aged to older adults have above-normal systolic blood pressure (SBP), i.e., SBP ≥120 mmHg, placing them at an increased risk for cardiovascular diseases, cognitive dysfunction, chronic kidney disease, and other chronic conditions of aging. This elevated SBP state is associated with the vascular risk factors endothelial dysfunction and stiffening of the large elastic (i.e., aorta and carotid) arteries. High-intensity short-duration inspiratory muscle strength training (IMST) represents a novel, time-efficient (~5 min/day) lifestyle intervention that lowers SBP in select patient populations. However, whether IMST lowers SBP in middle-aged to older adults with above-normal SBP, or improves arterial function in any population, remains unknown.
Purpose: To determine whether high-intensity short-duration IMST lowers SBP and improves arterial function in otherwise healthy middle-aged to older adults with above-normal SBP.
Methods: Thirteen middle-aged and older (50–79 years) men and post-menopausal women with resting SBP ≥120 mmHg underwent 6 weeks of IMST (30 breaths/day; 6 days/week; 75% maximum inspiratory pressure [PIMAX]) (n=7, 2M/5F, age: 68 ± 2 years) or sham (15% PIMAX) training (n=6, 3M/3F, age: 67 ± 3 years) in a randomized, double-blind, sham-controlled study. Subjects underwent testing for BP (resting and 24-hour ambulatory [AMBP]), vascular endothelial function (brachial artery flow-mediated dilation [FMDBA]) and arterial stiffness (carotid-femoral pulse wave velocity [CFPWV], carotid artery compliance and β-stiffness index) before and after the intervention.
Results: Resting SBP was significantly lower after vs. before IMST (pre: 137 ± 4 mmHg, post: 127 ± 5 mmHg; p=0.001), but not sham training (pre: 134 ± 5 mmHg, post: 130 ± 5 mmHg; p=0.13). No changes in resting diastolic BP (DBP) or AMBP (24-hour, daytime, and nighttime measures of SBP and DBP) were observed in either group (all p>0.05). FMDBA was increased after IMST (pre: 4.2 Δ%, post: 6.3 Δ%; p=0.001), but not in response to sham training (pre: 3.2 Δ%, post: 3.2 Δ%; p=0.99), such that FMDBA was significantly higher in the IMST group compared to sham post-intervention (p=0.01). There were no changes in CFPWV, or carotid artery compliance or β-stiffness with training in either group (all p>0.05), nor were body weight, body composition, fasting plasma lipids or fasting blood glucose concentrations altered with IMST or sham training (all p>0.05).
Conclusion: These findings suggest that, independent of changes in other conventional CVD risk factors, high-intensity short-duration IMST may be an effective lifestyle-based approach to lower resting (casual) SBP and improve vascular endothelial function in middle-aged and older men and women with above-normal initial levels of resting SBP.
Daniel H Craighead, Thomas C Heinbockel, Matthew J Rossman, Lindsey R Jankowski, Rachel A Jackman, E Fiona Bailey, Michel Chonchol, Douglas R Seals
[link url="https://www.sciencedaily.com/releases/2019/04/190408161643.htm"]University of Colorado at Boulder material[/link]
[link url="https://www.fasebj.org/doi/10.1096/fasebj.2019.33.1_supplement.541.4"]FASB Journal abstract[/link]