Does a history of childbirth impact injury prevalence and mental health in female military members?

The effect of parity status on the prevalence and impact of musculoskeletal injury (MSKi) among female Canadian Armed Forces (CAF) members is unknown. This study aims to identify whether a history of childbirth and pregnancy-related complications are associated with MSKi occurrence among female members of the CAF. From September 2020 to February 2021, data were collected via an online questionnaire that assessed MSKi, reproductive health, and barriers to recruitment and retention in the CAF. Actively serving, female members were included in this analysis stratified by parous (n = 313) or nulliparous (n = 435) status. Descriptive analysis and binary logistic regressions were used to identify prevalence and adjusted odds ratios (aOR) of repetitive strain injuries (RSI), acute injuries, and body regions affected. Covariates included in aOR: age, body mass index, and rank. A p value of <0.05 was considered significant and 95% confidence intervals (CI) were reported. Female members with a history of childbirth were more likely to report an RSI (80.9% vs. 69.9%, OR = 1.57, CI: 1.03 to 2.40), and when stratified by body region, were more likely to have an RSI of the wrist (30.0% vs. 20.5%, aOR = 1.62, CI: 1.09 to 2.40), and foot (39.3% vs. 24.1%, aOR = 1.79, CI: 1.24 to 2.59). When compared to the nulliparous group, parity did not influence prevalence of acute injuries. MSKi and mental health perceptions were different for females who experienced postpartum depression, miscarriage, or preterm birth. Childbirth and pregnancy-related complications impact prevalence of some RSI among female CAF members. Thus, specific health and fitness support may be needed for parous female CAF members.

Sex disparities in self-reported musculoskeletal injuries in the Canadian Armed Forces.

Recent comprehensive systematic reviews indicate that females are at greater risk of musculoskeletal injuries (MSKi) than males in military populations. Considering the Canadian Armed Forces (CAF) goal of increasing female representation in the next few years, exploring these trends is essential. We aimed to determine the association between biological sex and MSKi in the CAF. An online survey was conducted with active-duty and former CAF members aged 18-65 years. Sex disparities in MSKi (acute or repetitive strain [RSI]) were analyzed using bivariate associations and binary logistic regressions with significance level at p < 0.05. Analyses were stratified by military environment (i.e., Army, Navy, and Air Force). From the 1947 respondents whose biological sex was reported, 855 were females and 1092 were males. Rates of RSI sustained by females and males while serving were 76.2% and 70.5% (p = 0.011), respectively, whereas 61.4% of females reported acute injuries compared to 63.7% of males (p = 0.346). Females were more likely to report overall RSI (adjusted odds ratio [aOR]: 1.397; 95% confidence intervals [CI]: 1.068-1.829), RSI having a greater impact on daily activities (aOR [95%CI]: 2.979 [2.093-4.239]) and greater impact on career progress/length (aOR [95%CI]: 1.448 [1.066-1.968]). Acute injuries, also more prevalent in females, were reported to have a greater impact on daily activities (aOR [95%CI]: 1.688 [1.198-2.379]). This study highlights sex disparities in MSKi prevalence and outcomes. Females within the CAF sample presented greater likelihood of reporting RSI, perceived impact of RSI on daily activities and career progress/length, and perceived impact of acute injuries on daily activities.

Fast adaptation in vestibular hair cells requires myosin-1c activity.

In sensory hair cells of the inner ear, mechanical amplification of small stimuli requires fast adaptation, the rapid closing of mechanically activated transduction channels. In frog and mouse vestibular hair cells, we found that the rate of fast adaptation depends on both channel opening and stimulus size and that it is modeled well as a release of a mechanical element in series with the transduction apparatus. To determine whether myosin-1c molecules of the adaptation motor are responsible for the release, we introduced the Y61G mutation into the Myo1c locus and generated mice homozygous for this sensitized allele. Measuring transduction and adaptation in the presence of NMB-ADP, an allele-specific inhibitor, we found that the inhibitor not only blocked slow adaptation, as demonstrated previously in transgenic mice, but also inhibited fast adaptation. These results suggest that mechanical activity of myosin-1c is required for fast adaptation in vestibular hair cells.