Inspiratory Muscle Strength Training: Acute Effects, Dynamic Improvements and Clinical Significance

Abstract

Inspiratory muscle strength training (IMST) is a form of resistive breathing training traditionally used to strengthen respiratory muscles. In our hands, we have reported significant reductions in blood pressure following six weeks of daily IMST that are driven in part by reductions in systemic vascular resistance. The work set forth in this dissertation addresses outstanding questions resulting from our previous work. Study 1 characterizes the acute cardiovascular and sympathetic response(s) to a single bout of IMST in healthy young adults. We show that IMST acutely increases heart rate with concomitant reductions in sympathetic nervous system outflow. Study 2 assesses the potential for six weeks IMST to alter the cardiovascular response to respiratory muscle fatigue in college-aged adults. The results of this study suggest IMST improves respiratory muscle endurance and as a result, blunts the blood pressure and heart rate responses to respiratory muscle fatigue. Finally, Study 3 documents the effects of six weeks IMST on overnight blood pressure and mediators of systemic vascular resistance in older adults diagnosed with obstructive sleep apnea. In a population that exhibits elevated blood pressure and sympathetic nervous system activity, we show that IMST significantly lowers daytime blood pressure, nighttime systolic blood pressure and resting sympathetic nervous system activity. These studies are the first to characterize the acute cardiovascular effects of IMST and to explore the effects of IMST on mediators of systemic vascular resistance in both healthy and patient populations.