Menstrual Function, Eating Disorders, Low Energy Availability, and Musculoskeletal Injuries in British Servicewomen.

PURPOSE: This study aimed to investigate associations between menstrual function, eating disorders, and risk of low energy availability with musculoskeletal injuries in British servicewomen. METHODS: All women younger than 45 yr in the UK Armed Forces were invited to complete a survey about menstrual function, eating behaviors, exercise behaviors, and injury history. RESULTS: A total of 3022 women participated; 2% had a bone stress injury in the last 12 months, 20% had ever had a bone stress injury, 40% had a time-loss musculoskeletal injury in the last 12 months, and 11% were medically downgraded for a musculoskeletal injury. Menstrual disturbances (oligomenorrhea/amenorrhea, history of amenorrhea, and delayed menarche) were not associated with injury. Women at high risk of disordered eating (Female Athlete Screening Tool score >94) were at higher risk of history of a bone stress injury (odds ratio (OR; 95% confidence interval (CI)), 2.29 (1.67-3.14); P < 0.001) and time-loss injury in the last 12 months (OR (95% CI), 1.56 (1.21-2.03); P < 0.001) than women at low risk of disordered eating. Women at high risk of low energy availability (Low Energy Availability in Females Questionnaire score ≥8) were at higher risk of bone stress injury in the last 12 months (OR (95% CI), 3.62 (2.07-6.49); P < 0.001), history of a bone stress injury (OR (95% CI), 2.08 (1.66-2.59); P < 0.001), a time-loss injury in the last 12 months (OR (95% CI), 9.69 (7.90-11.9); P < 0.001), and being medically downgraded with an injury (OR (95% CI), 3.78 (2.84-5.04); P < 0.001) than women at low risk of low energy availability. CONCLUSIONS: Eating disorders and risk of low energy availability provide targets for protecting against musculoskeletal injuries in servicewomen.

Hormonal contraceptive prescriptions in the UK Armed Forces.

INTRODUCTION: Thirty four per cent of women use hormonal contraceptives in the UK and the contraceptive pill is the most common method. There are no comparable data in the UK Armed Forces, but servicewomen are often required to complete physically arduous job roles in combat zones and may be more likely to take contraceptives to control or stop menstrual bleeding than the general population. We explored the prevalence of hormonal contraceptive prescriptions in the UK Armed Forces. METHODS: The study used defence medical records (Defence Medical Information Capability Programme) to identify hormonal contraceptive prescriptions for all serving regular UK servicewomen (n=15 738) as of 1 September 2017. RESULTS: Thirty one per cent of servicewomen (Royal Navy, 28%; British Army, 30%; Royal Air Force, 34%) had a current prescription for a hormonal contraceptive. Non-officer ranks were more likely to have a prescription for a hormonal contraceptive (32%) than officers (27%) (p<0.01). The contraceptive pill was more commonly prescribed (68%) than long-acting reversible contraceptive methods (32%) (contraceptive injection, 11%; contraceptive implant, 11%; intrauterine device, 10%). CONCLUSION: Prescription data suggest that the prevalence of hormonal contraceptive use in UK servicewomen is comparable with the general UK population. These findings suggest that military service does not influence prevalence or choice of hormonal contraceptives.

Menstrual disturbances in British Servicewomen: A cross-sectional observational study of prevalence and risk factors.

Female athletes are at increased risk of menstrual disturbances. The prevalence of menstrual disturbances in British Servicewomen and the associated risk factors is unknown. All women under 45 years in the UK Armed Forces were invited to complete a survey about demographics, menstrual function, eating and exercise behaviors, and psychological well-being. 3,022 women participated; 18% had oligomenorrhoea or amenorrhoea in the last 12 months, 25% had a history of amenorrhoea, and 14% had delayed menarche. Women who sleep ≥ 8 h were at a lower risk of a history of amenorrhoea than women who sleep ≤ 5 h [odds ratio (95% confidence intervals) = 0.65 (0.48, 0.89), p = 0.006]. Women who completed > 10 days of field exercise in the last 12 months were at higher risk of a history of amenorrhoea than women completing no field exercise [1.45 (1.13, 1.85), p = 0.004]. Women at high risk of an eating disorder (FAST score >94) were at higher risk of oligomenorrhoea or amenorrhoea [1.97 (1.26, 3.04), p = 0.002] and history of amenorrhoea [2.14 (1.63, 2.79), p < 0.001]. Women with symptoms of anxiety or depression were at higher risk of a history of amenorrhoea [1.46 (1.20, 1.77) and 1.48 (1.22, 1.79), p < 0.001]. British Servicewomen had a similar prevalence of menstrual disturbances to some endurance athletes. Eating disorders, sleep behaviors, and management of mental health, provide targets for protecting health of the reproductive axis.

Reproductive and metabolic adaptation to multistressor training in women.

Hypothalamic-pituitary-gonadal (HPG) axis suppression in exercising women can be caused by low energy availability (EA), but the impact of a real-world, multistressor training environment on reproductive and metabolic function is unknown. This study aimed to characterize reproductive and metabolic adaptation in women undertaking basic military training. A prospective cohort study in women undertaking 11-month initial military training (n = 47) was carried out. Dynamic low-dose 1-h gonadotrophin-releasing hormone (GnRH) tests were completed after 0 and 7 mo of training. Urine progesterone was sampled weekly throughout. Body composition (dual X-ray absorptiometry), fasting insulin resistance (homeostatic modeling assessment 2, HOMA2), leptin, sex steroids, anti-Müllerian hormone (AMH), and inhibin B were measured after 0, 7, and 11 mo with an additional assessment of body composition at 3 mo. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses were suppressed after 7 mo (both P < 0.001). Among noncontraceptive users (n = 20), 65% had regular (23-35 days) cycles preenrollment, falling to 24% by 7 mo of training. Of women in whom urine progesterone was measured (n = 24), 87% of cycles showed no evidence of ovulation. There was little change in AMH, LH, and estradiol, although inhibin B and FSH increased (P < 0.05). Fat mass fluctuated during training but at month 11 was unchanged from baseline. Fat-free mass did not change. Visceral adiposity, HOMA2, and leptin increased (all P < 0.001). HPG axis suppression with anovulation occurred in response to training without evidence of low EA. Increased insulin resistance may have contributed to the observed pituitary and ovarian dysfunction. Our findings are likely to represent an adaptive response of reproductive function to the multistressor nature of military training.NEW & NOTEWORTHY We characterized reproductive endocrine adaptation to prolonged arduous multistressor training in women. We identified marked suppression of hypothalamic-pituitary-gonadal (HPG) axis function during training but found no evidence of low energy availability despite high energy requirements. Our findings suggest a complex interplay of psychological and environmental stressors with suppression of the HPG axis via activation of the hypothalamic-pituitary adrenal (HPA) axis. The neuroendocrine impact of nonexercise stressors on the HPG axis during arduous training should be considered.

Tibial Macrostructure and Microarchitecture Adaptations in Women During 44 Weeks of Arduous Military Training.

Bone adapts to unaccustomed, high-impact loading but loses mechanosensitivity quickly. Short periods of military training (≤12 weeks) increase the density and size of the tibia in women. The effect of longer periods of military training, where the incidence of stress fracture is high, on tibial macrostructure and microarchitecture in women is unknown. This observational study recruited 51 women (age 19 to 30 years) at the start of 44 weeks of British Army Officer training. Tibial volumetric bone mineral density (vBMD), geometry, and microarchitecture were measured by high-resolution peripheral quantitative computed tomography (HRpQCT). Scans of the right tibial metaphysis (4% site) and diaphysis (30% site) were performed at weeks 1, 14, 28, and 44. Measures of whole-body areal bone mineral density (aBMD) were obtained using dual-energy X-ray absorptiometry (DXA). Blood samples were taken at weeks 1, 28, and 44, and were analyzed for markers of bone formation and resorption. Trabecular vBMD increased from week 1 to 44 at the 4% site (3.0%, p < .001). Cortical vBMD decreased from week 1 to 14 at the 30% site (-0.3%, p < .001). Trabecular area decreased at the 4% site (-0.4%); trabecular bone volume fraction (3.5%), cortical area (4.8%), and cortical thickness (4.0%) increased at the 4% site; and, cortical perimeter increased at the 30% site (0.5%) from week 1 to 44 (p ≤ .005). Trabecular number (3.5%) and thickness (2.1%) increased, and trabecular separation decreased (-3.1%), at the 4% site from week 1 to 44 (p < .001). Training increased failure load at the 30% site from week 1 to 44 (2.5%, p < .001). Training had no effect on aBMD or markers of bone formation or resorption. Tibial macrostructure and microarchitecture continued to adapt across 44 weeks of military training in young women. Temporal decreases in cortical density support a role of intracortical remodeling in the pathogenesis of stress fracture. © 2021 Crown copyright. Journal of Bone and Mineral Research © 2021 American Society for Bone and Mineral Research (ASBMR). This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland.

Measuring the Exercise Component of Energy Availability during Arduous Training in Women.

INTRODUCTION: Low energy availability (EA) may impede adaptation to exercise, suppressing reproductive function and bone turnover. Exercise energy expenditure (EEE) measurements lack definition and consistency. This study aimed to compare EA measured from moderate and vigorous physical activity from accelerometry (EEEmpva) with EA from total physical activity (EEEtpa) from doubly labeled water in women. The secondary aim was to determine the relationship of EA with physical fitness, body composition by dual-energy x-ray absorptiometry, heart rate variability (HRV), and eating behavior (Brief Eating Disorder in Athletes Questionnaire [BEDA-Q]). METHODS: This was a prospective, repeated-measures study, assessing EA measures and training adaptation during 11-month basic military training. Forty-seven women (23.9 ± 2.6 yr) completed three consecutive 10-d assessments of EEEmvpa, EEEtpa, and energy intake (EI). EA measures were compared using linear regression and Bland-Altman analyses; relationships of EA with fat mass, HRV, 1.5-mile run times, and BEDA-Q were evaluated using partial correlations. RESULTS: EA from EEEmvpa demonstrated strong agreement with EA from EEEtpa across the measurement range (R2 = 0.76, r = 0.87, P < 0.001) and was higher by 10 kcal·kg-1 FFM·d-1. However, EA was low in absolute terms because of underreported EI. Higher EA was associated with improved 1.5-mile run time (r = 0.28, P < 0.001), fat mass loss (r = 0.38, P < 0.001), and lower BEDA-Q score (r = -0.37, P < 0.001) but not HRV (all P > 0.10). CONCLUSION: Accelerometry-based EEE demonstrated validity against doubly labeled water during multistressor training, the difference representing 10 kcal·kg-1 FFM·d-1 EEE from nonexercise activity. Beneficial physical but not autonomic adaptations were associated with higher EA. EAmvpa and BEDA-Q warrant consideration for low EA assessment and screening.

Skeletal responses to an all-female unassisted Antarctic traverse.

PURPOSE: To investigate the skeletal effects of the first all-female trans-Antarctic traverse. METHODS: Six women (mean ±â€¯SD, age 32 ±â€¯3 years, height 1.72 ±â€¯0.07 m, body mass 72.8 ±â€¯4.0 kg) hauled 80 kg sledges over 1700 km in 61 days from coast-to-coast across the Antarctic. Whole-body areal bone mineral density (aBMD) (dual-energy X-ray absorptiometry) and tibial volumetric BMD (vBMD), geometry, microarchitecture and estimated mechanical properties (high-resolution peripheral quantitative computed tomography) were assessed 39 days before (pre-expedition) and 15 days after the expedition (post-expedition). Serum and plasma markers of bone turnover were assessed pre-expedition, and 4 and 15 days after the expedition. RESULTS: There were reductions in trunk (-2.6%), ribs (-5.0%) and spine (-3.4%) aBMD from pre- to post-expedition (all P ≤ 0.046); arms, legs, pelvis and total body aBMD were not different (all P ≥ 0.075). Tibial vBMD, geometry, microarchitecture and estimated mechanical properties at the metaphysis (4% site) and diaphysis (30% site) were not different between pre- and post-expedition (all P ≥ 0.082). Bone-specific alkaline phosphatase was higher 15 days post- than 4 days post-expedition (1.7 µg∙l-1, P = 0.028). Total 25(OH)D decreased from pre- to 4 days post-expedition (-36 nmol∙l-1, P = 0.008). Sclerostin, procollagen 1 N-terminal propeptide, C-telopeptide cross-links of type 1 collagen and adjusted calcium were unchanged (all P ≥ 0.154). CONCLUSION: A decline in aBMD of the axial skeleton may be due to indirect and direct effects of prolonged energy deficit. We propose that weight-bearing exercise was protective against the effects of energy deficit on tibial vBMD, geometry, microarchitecture and strength.