Characterizing Reproductive Health, Bone Health Markers, and Musculoskeletal Injuries in Canadian Armed Forces Members and Across the Female Lifespan

Abstract

Reproductive health characteristics (e.g., parity status, menstrual regularity) are demonstrated to have an impact on the occurrence of musculoskeletal injury (MSKi) and bone health across the female lifespan. As well, these relationships extend to female military members; however, the association between reproductive health, bone health and the risk of MSKi have yet to be elucidated in female Canadian Armed Forces (CAF) members. This multi-stage, interdisciplinary approach examining the relationship between reproductive health and injury risk across the female lifespan included: i) a self-report questionnaire where reproductive health and MSKi data were collected and examine among female CAF members; ii) the validation of an ultrasound device to assess bone mineral density (BMD); iii) physical testing where physical fitness (e.g., VO2max, bench press), reproductive health hormones, and their influence on BMD; iv) a cross-sectional study that examined the impact of objectively measured behavioural (e.g., physical activity and sleep) and reproductive factors and their association with BMD in a pregnant population; and v) a five-year longitudinal study examining the impact of the menopause transition on BMD. It was determined that female CAF members who experience endometriosis and menstrual irregularity were more like to have an acute injury and repetitive strain injury, respectively. With the use of a linear regression to transform the output from the UltraScan650™, the ultrasound device was both a valid and reliable way to assess BMD and was used to determined that female CAF members who are parous and used hormonal birth control (HBC) have higher BMD compared to their nulliparous and non-HBC using peers. Further, cardiorespiratory fitness was the greatest predictor of BMD, and the ratio of estradiol/progesterone was a significant predictor of BMD. Among pregnant individuals, longer sleep was linked to lower BMD and age predicted BMD among those in their third trimester and who experienced exposure to HBC. In the menopause cohort, having higher follicle-stimulating hormone (FSH) across their menopause transition was linked to a greater decline in BMD and serum calcium was negatively associated with BMD. Thus, reproductive health should be considered when developing injury prevention programs for female CAF members. More research in CAF population is required as it relates to pregnant and menopausal populations to develop injury prevention programs suitable for the life-stage.