On The Science Of Sex Differences: An In-Depth Study On Muscle Force And Neuromuscular Fatigue

This dissertation seeks to explore the biological and neurophysiological factors that contribute to sex differences in maximal force expression and neuromuscular fatigue development. While it is known that many aspects of human physiology differ between males and females, the extent to which these differences influence performance is not yet fully understood. Unfortunately, sex differences in human physiology are often understudied and overlooked in research and clinical practice, despite significant advances in our understanding of the human body. This dissertation seeks to fill this gap by examining the current state of knowledge on sex differences in human physiology (Background Chapter) and presenting new insights into the mechanisms underlying these differences (Study One and Study Two). In pursuit of this objective, the initial study of this thesis centered on elucidating the sexual dimorphism in maximal force production, with a focus on understanding the underlying physiological mechanisms. In doing so, the determinants of maximal force expression were studied from a neurophysiological standpoint, and their biological associations were investigated. Moreover, this first study can be considered as a comprehensive characterization of the biological sex differences observed within our cohort of participants. On the other hand, the second study focused on elucidating the differences in neuromuscular fatigue between males and females. With an emphasis on understanding the reasons for the lower neuromuscular fatigue development that has been consistently reported for females in the literature, the second study sought to unravel the mechanisms that may underlie these differences. Through a comprehensive analysis of various determinants of fatigue, from the central to the peripheral components, the study aimed to shed light on the potential factors contributing to the observed sex differences in neuromuscular fatigue development.