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Abstract

Purpose: This dissertation comprised three studies that examined the physiological, neurophysiological, and psychosocial mechanisms underlying sex differences in the multidimensional experience of exertional dyspnea. Methods: Study #1 (chapter 2) compared physiological, perceptual, and psychosocial factors between males and females who did versus did not select unsatisfied inspiration at peak exercise. Study #2 (chapter 3) investigated the effects of added ventilatory loading (dead space customized to 15 % of forced vital capacity) on sex differences in respiratory mechanics, neurophysiological responses, and the multidimensional components of exertional dyspnea. Study #3 (chapter 4) evaluated how relative dead space loading influenced respiratory muscle activation patterns and pressure generation in males and females. All studies used maximal incremental cycling exercise. Conclusions: We found that smaller absolute lung volumes were associated with higher intensity ratings of unsatisfied inspiration during exercise, and psychosocial factors, such as gender and anxiety, emerged as important contributors to sex differences in dyspnea perception (chapter 2). Although males and females exhibited distinct cardiorespiratory, respiratory mechanical, and neurophysiological responses, as well as respiratory muscle activation patterns with added dead space loading, these differences did not consistently translate to altered dyspnea perception during maximal cycling (chapters 3-4). Collectively, these findings suggest that despite well-established sex differences in respiratory anatomy and physiology, males and females appear to employ distinct reflexive respiratory muscle activation patterns that result in comparable perceptions of exertional dyspnea. Collectively, this work emphasizes that exertional dyspnea cannot be attributed to a single mechanism but instead reflects the complex interplay of anatomical, physiological, and psychosocial factors. Recognizing the reflexive respiratory muscle activation patterns in males and females may guide future research aimed at refining clinical assessment and developing more personalized approaches to managing dyspnea in aging populations and patient groups.