Ask the doctors: Resistive breath training could lower blood pressure

Dear Doctor: A good friend of mine is into this new thing called resistive breath training. She says it helps runners build endurance, and she even bought a breathing gadget to practice it. Does it really help?

Dear Reader: Resistive breath training, also known as inspiratory muscle strength training (IMST), is a type of resistance training for the muscles we use to breathe. It can be accomplished through a series of controlled breathing exercises or, as your friend is planning, with a hand-held device. Known as an inspiratory muscle trainer, this type of device typically consists of a mouthpiece through which the person breathes and some sort of adjustable valve that creates varying degrees of resistance for the exerciser to work against.

While IMST may not be familiar to you and your friend, it’s not actually a new technique. Resistive breath training was developed many decades ago to help people with various breathing problems, including COPD, asthma and the after-effects of bronchitis. It is also used to help people to successfully withdraw from mechanically assisted breathing.

In a study dating back to 1979, researchers found that IMST helped patients living with severe COPD to achieve improved breath control, as well as improved expectoration, the ejection of phlegm and mucus from throats and lungs. Subsequent studies continued to find benefits in the practice.

It’s possible that your friend’s interest in IMST arises from a spate of news reports about preliminary findings by researchers from the University of Colorado, which were presented last month at the annual Experimental Biology conference.

The seed for the experiments was planted several years ago, when researchers from the University of Arizona looked into IMST as a way to help individuals living with obstructive sleep apnea. This is a potentially serious disorder in which muscles in the throat relax enough during sleep to completely block airways. In addition to confirming that by increasing resistance, the length of each IMST session could be shortened, the Arizona researchers saw a surprising side effect. After six weeks of therapy, systolic blood pressure in the study participants dropped significantly. Systolic blood pressure – that’s the top number in a blood pressure reading – is the pressure in the blood vessels during a heartbeat. (The bottom number is the pressure in the blood vessels between heartbeats.) High blood pressure is one of the major risk factors for cardiovascular disease, which is the leading cause of death in the United States.

The results of the Arizona research spurred scientists at the University of Colorado to build upon the findings. In their own series of experiments, which are ongoing, the Colorado researchers saw the same significant drop in blood pressure in participants who performed IMST. They also recorded improvements to large-artery function. The IMST group also saw improvement in cognitive function and in endurance and heart-lung efficiency while exercising on a treadmill. Neither of those changes were seen in a control group, which used a breathing device that delivered only low resistance.

These results are impressive, but, as the researchers themselves point out, they are preliminary. The researchers stress, and we agree, that anyone considering IMST should first check with their doctor.