Researchers at the University of Arizona College of Medicine – Tucson, a part of UArizona Health Sciences, are launching a Phase II clinical trial to assess the long-term effectiveness of a unique respiratory training protocol known as “inspiratory muscle training” for reducing blood pressure and improving cardiovascular health in adults with obstructive sleep apnea.
E. Fiona Bailey, PhD, a professor in the Department of Physiology at the UArizona College of Medicine – Tucson, was awarded a five-year, $3.4 million grant from the National Institute on Aging, a division of the National Institutes of Health, to build on her group’s previous research that showed a respiratory workout entailing 30 breaths a day can lower blood pressure.
“High blood pressure is a major risk factor for cardiovascular disease, which is the number one cause of death in America. Five minutes a day of inspiratory muscle training, consisting of just 30 inspiratory efforts against resistance, offers a low-cost, non-pharmacologic means of improving both sleep quality and blood pressure,” said Dr. Bailey, who specializes in respiratory physiology.
Obstructive sleep apnea is a serious health condition in which the muscles of the throat relax during sleep and collapse inward so that air cannot reach the lungs for a short period. This causes oxygen deprivation and repeated awakening from sleep. Together, nightly oxygen deprivation and the inability to achieve uninterrupted sleep contribute to an increased risk of developing high blood pressure and cardiovascular disease. Prior research has shown obstructive sleep apnea affects about 50% of adults in the U.S. and nearly 1 billion people worldwide.
The new clinical trial will provide an opportunity for Dr. Bailey and her research team, which includes collaborators at the University of Colorado at Boulder, to implement inspiratory muscle training over six months in a larger group of 50-to-80-year-old adults with obstructive sleep apnea and above-normal blood pressure. The team will follow up with participants three months after the training ends to see how long the blood pressure-lowering effects last.
Study participants will undergo initial screenings of cardiovascular, respiratory and sleep health. Eligible participants will be randomly assigned to one of two training groups, one emphasizing high resistance training the other emphasizing low resistance training. Participants in both groups will perform their training at home and complete 30 breaths per day, 5 days a week, for 24 weeks.
Inspiratory muscle training originally was devised for use by athletes and people with breathing problems, such as chronic obstructive pulmonary disease, asthma and bronchitis. Dr. Bailey has adapted the protocol for everyday use by adults with obstructive sleep apnea. In its current format, inspiratory muscle training can be performed at home, at work or when travelling, using a hand-held training device similar to an inhaler.
Results of early studies by Dr. Bailey’s group showed inspiratory muscle training builds respiratory muscle strength and has a surprising secondary benefit – it lowers blood pressure. The reduction in blood pressure is greater than that gained from traditional aerobic exercise and in many instances, can exceed reductions achieved with blood pressure medications. The results of this early work are published in the journals Sleep and Journal of Applied Physiology.
Continuous positive airway pressure, or CPAP, is the standard therapy for obstructive sleep apnea and is effective at reducing oxygen deprivation during sleep, but many users discover they are unable to tolerate it throughout the night.
Regular aerobic exercise can help and is important for cardiovascular health, but current recommendations are for 150 minutes per week of moderate intensity exercise. This amount of exercise can be a difficult to achieve – fewer than 30% of American adults meet this minimum – and may be especially challenging for adults with obstructive sleep apnea, many of whom experience chronic fatigue and excess daytime sleepiness.
“New cost-effective and time-efficient strategies are needed to manage the health issues caused by obstructive sleep apnea,” said Dr. Bailey, also a member of the BIO5 Institute. “It is vitally important that we devise new approaches to help people keep their blood pressure under control and improve cardiovascular health.”
Dr. Bailey’s prior findings recently were confirmed by collaborators Drs. Douglas Seals and Daniel Craighead at the University of Colorado Boulder Department of Integrative Physiology. In that study, they demonstrated that six weeks of inspiratory muscle strength training by older adults with above-normal blood pressure reduced blood pressure and improved arterial health, contributing to an overall reduction in the risk of developing cardiovascular disease.
Research discussed in this publication is supported by the National Institute of Aging, a unit of the National Institutes of Health (R01AG065346-01A1). This project is approved by the University of Arizona Institutional Review Board.
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Jo Marie Barkley