ABSTRACT
This chapter reviews the literature on the nature and source(s) of increased activity-related dyspnea in otherwise healthy pregnant women and in obese adults with a body mass index ≥30 kg/m2. In both pregnancy and obesity, the central neural drive to breathe is increased and there are measureable abnormalities of respiratory mechanics that, when combined, could lead to increased neuromechanical uncoupling of the respiratory system and attendant respiratory discomfort. The chapter outlines the pregnancy- and obesity-related changes in ventilatory control and in static and dynamic respiratory mechanical/muscular function and determines their potential contribution to the perception of increased dyspnea that arises during physical activity. It focuses on the effects of moderate obesity in otherwise healthy individuals who do not have comorbidities that could contribute to exercise intolerance. Neural respiratory motor drive is elevated in the pregnant compared with the postpartum or nonpregnant state.
