In the United States, more than 65% of individuals above the age of 50 have hypertension (abnormally high blood pressure). The occurrence of hypertension increases with age and is responsible for 7.6 million deaths per year globally (13.5% of total mortality). Additionally, 54% of strokes and 47% of cardiovascular disease (CVD, the leading cause of death worldwide) are attributable to high blood pressure. These factors make interventions targeting hypertension an effective means by which to improve the health and lifespan of an aging population. Pharmaceutical interventions are effective in treating hypertension but come with a multitude of side effects. As is often the case, exercise is a potent therapy for preventing age-related diseases such as hypertension; however, according to the CDC, only 5% of adults engage in the minimum recommended daily exercise required to reduce such diseases. New research might offer an alternative for those individuals who lack the time, motivation, or physical capacity to achieve the amount of daily exercise required to control hypertension and to stave off the deleterious effects of chronically elevated blood pressure.
A modified version of a technique known as inspiratory muscle strength training (IMST), a therapy originally developed to treat pulmonary disorders (e.g., COPD, sleep apnea), is showing significant potential in replicating various effects of daily exercise with to regard to cardiovascular health. Muscles involved in breathing can be strengthened by simply inhaling and exhaling for multiple uninterrupted repetitions through a handheld device similar in appearance to an asthma inhaler, which has the benefit of being low-tech, portable, and affordable.
The Journal of the American Heart Association recently published research by Craighead et al. wherein they utilize a high-resistance paradigm of IMST. Individuals aged 50-79 years having abnormally high blood pressure, but otherwise healthy, participated in a study examining the application of this modified form of IMST. Participants were required to perform 30 repetitions 5–7 times per week, which took a total of approximately 25–35 minutes each week. Study participants adhering to the regimen saw a change in their systolic blood pressure from around 135 mmHg to around 126 mmHg, a reduction that could, if persistent, correlate to a 30%–40% lower risk of death from CVD. These benefits are comparable to those seen in individuals who perform 150 minutes/week of moderate exercise. Notably, reduction in diastolic blood pressure was less than that seen for systolic blood pressure; however, the initial diastolic blood pressure for all subjects was normal, in contrast to elevated systolic blood pressure. Moreover, diastolic blood pressure is not known to increase with age.
In addition to blood pressure, the researchers observed improvements to a number of other facets known to be implicated in CVD, including endothelial function. The endothelium is a thin membrane of specialized cells lining the vascular walls, in part functioning to control the relaxation and contraction of blood vessels. Proper endothelial function is vital to healthy cardiovascular function and is also known to diminish with age. Craighead et al. report a 45% increase of flow-mediated dilation of the brachial artery (FMDBA), a clinical diagnostic that assesses the ability of a blood vessel to widen in response to an increase in blood flow volume. The increase of FMDBA in the treatment group correlated to a risk reduction of CVD incidence of 20–35%. A blood vessel’s ability to expand when subjected to increased blood flow is mediated by nitrous oxide (NO); not surprisingly, subjects undergoing IMST treatment were shown to have increased bioavailability of circulating NO.
This research explores IMST as a novel alternative to aerobic exercise that provides equivalent efficacy with regard to improving markers of cardiovascular function, yet requires a fraction of the time and physical exertion, resulting in greater adherence. All factors combine make this an ideal therapeutic for an aged population.