The relevance of depression in the clinical realm is well known, as it is one of the most common mental disorders in the United States. Clinical depression is the leading cause of disease for women worldwide. The sex difference in depression and anxiety has guided the research of not just recent studies but older studies as well, supporting the theory that gonadal hormones are associated with the mechanisms of emotional cognition. The scientific literature points towards a clear correlative relationship between gonadal hormones, especially estrogens, and emotion regulation. This thesis investigates the neural pathways that have been indicated to regulate mood and anxiety. Currently, the research points to the hypothalamic-pituitary-adrenal axis, which regulates the stress response through its ultimate secretion of cortisol through the adrenal cortex, and its modulated response when exposed to higher levels of estrogen. Another mechanism that has been investigated is the interaction of estrogen and the serotonergic system, which is noteworthy because the serotonergic system is known for its importance in mood regulation. However, it is important to note that the research seeking to determine the neurobiological underpinnings of estrogen and the serotonergic system is not expansive. Future research should focus on determining the direct relationship between cortisol hypersecretion and estrogens, the specific neurobiological effects of serotonergic receptor subtypes on the antidepressant actions of estrogens, and the simultaneous effects of the stress and serotonergic systems on depressive symptoms.

This thesis reviewed variables of baseball mechanics and performance as discussed in current literature. This included investigating factors of biomechanics, the health of players, and comparisons across demographics. At the biomechanical level, components of the kinetic chain were observed as the energy transferred from the lower body to the upper body. Additionally, the upper body appeared to compensate for deficits in the rotation of the trunk. Injuries to the abdominal and low back were correlated with trunk rotation, while arm injuries were traced back to overuse and fatigue. When considering experience level, variation tended to decrease. Youth players demonstrated different patterns of fatigue and different injury correlates compared to adults. At a geographic level, American pitchers may be associated with an increased risk of elbow injuries, with Japanese and Korean pitchers to shoulder injuries; these differences are thought to be due to differences in instruction. Applying this research and findings to current baseball players may help guide training and performance or continue research.