Measuring the impact of a twelve-week aerobic training program on respiratory parameters using AirgoTM

The aim of this work was to investigate the effects of a twelve-week moderate intensity aerobic exercise program on respiratory health of previously sedentary adults. Moreover, the hypothesis that sigh breath variability in terms of both rate and amplitude could be an indicator of lung health was tested for the first time. The work will be presented in six chapters, the content of which is briefly summarized below. The first chapter of this thesis provides a general description of the respiratory system. The second chapter provides a review of the measurements performed to assess the health status of the respiratory system. Both time parameters such as respiratory rate and lung volumes and capacities such as tidal volume are described, and their meaning is explained. The third chapter introduces the concept of respiratory variability. Both random and nonrandom respiratory variability are discussed, explaining how the respiratory system adapts and responds to external stimuli in order to maintain homeostasis. Similarly to heart rate variability, nonrandom respiratory variability appears to be functional and healthy. Furthermore, this chapter discusses the theme of sigh breaths. A definition of sighing is provided, along with the description of central and peripheral physiological factors that influence sighing. Lastly, the hypothesis that sighs serve as s physiological resetters of optimal respiratory regulation is covered. Among other things, according to this hypothesis randomness in respiratory variability should increase while approaching the next sigh, and, following a spontaneous sigh, autocorrelation in breathing parameters should be reset. This hypothesis has been investigated in this work, and significant results have been obtained. Chapter four describes AirgoTM, the device through which all data used in the present work was acquired. The recorded signal is a measure of resistance of the belt which is placed around the subject’s chest in a patented position: the resistance of the belt changes accordingly to the expansion and contraction of the subject’s chest, capturing movements of both the rib cage and the diaphragm. The fifth chapter describes the participants, methods and results of the study Brain Age and Exercise: A Trial of Aerobic Exercise to Improve Brain Health in Older Adults, conducted by An Ouyang and his collaborators in Boston, MA. The aim of the study was to investigate the effects of a twelve-week aerobic exercise program on previously sedentary adults. Cardiovascular fitness, cognitive performance and sleep quality were considered. The AirgoTM device was worn continuously by the participants: the data acquired was stored and left for future analysis, which was the focus of this thesis. The last chapter provides a detailed description of the procedures followed to analyze AirgoTM data coming from the study conducted by An Ouyang and his collaborators in Boston, MA. Daytime and nighttime were analyzed separately. For daytime analysis, resting state was isolated using an automated algorithm. Moreover, sighs were identified in the signal using another automated algorithm. Changes in time and volume parameters were sought comparing data acquired at the beginning of the program, taken as baseline, with data acquired at the end. The hypothesis that sighs may serve as respiratory variability resetters was investigated using data acquired throughout the exercise program.