Susan P. Proctor’s research while affiliated with U.S. Army Research Institute of Environmental Medicine and other places

Background Body composition influences physical fitness (PF) and risk of musculoskeletal injury (MSKI). Assessing the relationship between body fat (BF), PF and MSKI risk in a large diverse military population may provide evidence basis informing health-care policies, practices, and programs for military and civilian populations. Objective Evaluate the validity of expedient methods to estimate BF (e.g., circumference-based equation (CBE) and bioelectrical impedance analysis (BIA)) and investigate relationships between BF and PF with MSKI risk in a large diverse population. Methods Participants were 1904 active-duty Soldiers (643 F) representing Army demographics sex, race/ethnicity (R/E), and age. PF, defined as the most recent Army Combat Fitness Test (ACFT) score and incidence of MSKI, were obtained from Army records. BF was determined by dual-energy x-ray absorptiometry (%BFDXA), bioelectrical impedance analysis (%BFBIA), and CBE using 3-site (Hodgdon, %BFHE) and 1-site (Taylor-McClung, %BFTM) equations. Results were stratified by race and sex, to evaluate differences in accuracy of estimated %BF (weighted root mean squared error from %BFDXA). Associations of BF and PF with MSKI risk were evaluated with logistic regression. Results CBE and BIA underestimated %BF compared to %BFDXA. %BFBIA differed from %BFDXA overall and by sex. %BFTM underestimation was uniform across both sex and R/E compared to %BFDXA. Mean differences from %BFDXA by sex (M;F) were lower when measured by %BFTM (4.38; 4.59) compared to %BFHE (5.88; 4.39). Individuals had a greater likelihood of MSKI if they failed BF standards (odds ratio 1.32). Scoring ≥ 540 total on ACFT exhibited a 31% (95% CI: 0.52, 0.92) lower MSKI risk during the following 12 months than those with a lower score. Conclusions A single-site BF equation (%BFTM) maintained similar accuracy across the Soldier population by sex, age, and R/E. Implementing a PF score threshold in lieu of passing Army BF standards was associated with lower MSKI risk.

Background Post-9/11 veterans were exposed to environmental and occupational pollutants during deployment. Objective Our aim was to determine associations between deployment-related exposures and sinusitis and rhinitis. Methods Between April 2018 and March 2020, veterans with land-based deployment after 9/11 who were living within 25 miles of 6 Department of Veteran Affairs medical centers were randomly chosen by using a Defense Manpower Data Center roster. Participants completed interviewer-administered questionnaires, which included a 32-item deployment exposure battery and self-report of rhinitis and health professional–diagnosed sinusitis. Exposure categories included burn pit smoke, combustion engine exhaust/ground dust, other open combustion sources, toxicants, and military job-related VGDF. Each item was scored on the basis of frequency and duration of exposure; ordinal scores were summed and scaled to 100 within each category. Odds ratios (ORs) were estimated using logistic regression for sinusitis and rhinitis separately. ORs were scaled per 20-point exposure score. Results Among the 1960 participants, the incidences of sinusitis and rhinitis with onset during deployment were 2.1% and 3.6%, respectively; the incidences of postdeployment onset were 5.1% and 5.6%, respectively. Toxicant exposure consisted mainly of “applying pesticide, insecticide, or repellent to your own skin or to your own clothing” and was associated with rhinitis with onset during deployment (OR = 1.50 [95% CI = 1.31-1.84]) and onset after deployment (OR = 1.21 [95% CI = 0.93-1.50]). There were no associations with burn pit smoke or other exposure categories. Conclusion Veterans with deployment exposures to toxicants were at increased risk of rhinitis, particularly during deployment. The clinical evaluation of postdeployment veterans should address rhinitis as a deployment-related condition.

Introduction Although bone formation has been observed in the distal tibia of trainees during Basic Combat Training (BCT), some animal studies have demonstrated greater mechanosensitivity in the juvenile compared to the mature skeleton. How age affects skeletal adaptations to military training is unknown. The purpose of this study was to determine if skeletal adaptations to US Army BCT differ by age. Methods We enrolled 2085 trainees (1303 males, 782 females). High-resolution peripheral quantitative computed tomography was used to assess total, cortical, and trabecular bone mineral density (BMD) and the microarchitecture of the distal tibia before and after 8 wk of BCT. Generalized linear models were used to compare mean percent change (95% confidence interval (CI)) in each bone parameter by age group (<20, 20–25, 26–29, and ≥30 yr) and to evaluate differences in bone parameter changes between age groups (effect estimates (95% CI)). Models were stratified by sex with multivariable adjustment. Results Male and female trainees in all age groups had increases in total BMD, trabecular BMD, and trabecular bone volume fraction from baseline ( P < 0.01 for all). Male and female trainees also had increases in trabecular thickness from baseline in all groups ( P < 0.05) except females ≥30 yr old. Female trainees 20–25 yr old had a significantly larger increase in trabecular thickness than those <20 yr old (effect estimate (95% CI), 0.33% (0.02%–0.64%); P < 0.05). Trabecular microarchitecture was largely not otherwise different between age groups for either sex. Male and female trainees <20 yr old had greater changes in cortical BMD compared to older age groups (males, P < 0.01; females, P < 0.05 for all). Conclusion Trainees <20 yr old experience the greatest improvements in cortical BMD at the distal tibia during US Army BCT, suggesting that adaptive bone formation in cortical bone may be attenuated with skeletal maturity. However, the mechanosensitivity of trabecular bone to exercise training remains intact regardless of age.

Objective The Automated Neuropsychological Assessment Metrics (ANAM) is a computerized cognitive test system used extensively with military service members. The aim of this study was to develop a nationally representative normative dataset of Army National Guard (ARNG) personnel and to explore potential relationships between ANAM performances and select military service, demographic, and health factors. Methods ANAM performance data were collected using standardized procedures from a representative sample of ARNG service members in six U.S. states. Normative performance values, stratified by age, sex, and military occupational category, were calculated for each ANAM subtest and descriptive measures were computed, along with base rates of below-average performance. The effect of demographic (e.g., age, sex, education, race) and military service and health factors (e.g., deployment, job category, history of head injury) was examined. Results Data from 1,436 ARNG service members (14.3% female) were analyzed, and normative values calculated. Overall, differences in ANAM performance based on demographic, military service, and health factors were small. A total of 8.9% of the sample had scores on two or more subtests that were ≥ 1.3 SD below the mean; this dropped to 1.9% using a more stringent cut point (≥2 SD below the mean). Conclusion The ANAM normative data reported herein ensure that healthcare providers and researchers have access to reference data that more accurately reflect the larger population of ARNG service members. These data support the assessment and management of ARNG service members’ health, as well as future ANAM research involving ARNG service members.

Objective Less than half of servicewomen report loss of menses during initial military training. However, self-reported menstrual status may not accurately reflect hypothalamic-pituitary-ovarian (HPO) axis suppression and may underestimate reproductive health consequences of military training. Our aim was to characterise HPO axis function during US Army Basic Combat Training (BCT) in non-hormonal contraceptive-using women and explore potential contributors to HPO axis suppression. Methods In this 10-week prospective observational study, we enrolled multi-ethnic women entering BCT. Trainees provided daily first-morning voided urine, and weekly blood samples during BCT. Urinary luteinising hormone, follicle stimulating hormone, and metabolites of estradiol and progesterone were measured by chemiluminescent assays (Siemens Centaur XP) to determine hormone patterns and luteal activity. We measured body composition, via dual-energy X-ray absorptiometry, at the beginning and end of BCT. Results Trainees (n=55) were young (mean (95% CI): 22 (22, 23) years) with average body mass index (23.9 (23.1, 24.7) kg/m ² ). Most trainees (78%) reported regular menstrual cycles before BCT. During BCT, 23 (42%) trainees reported regular menses. However, only seven trainees (12.5%) had menstrual cycles with evidence of luteal activity (ELA) (ie, presumed ovulation), all with shortened luteal phases. 41 trainees (75%) showed no ELA (NELA), and 7 (12.5%) were categorised as indeterminant. Overall, women gained body mass and lean mass, but lost fat mass during BCT. Changes in body mass and composition appear unrelated to luteal activity. Conclusions Our findings reveal profound HPO axis suppression with NELA in the majority of women during BCT. This HPO axis suppression occurs among women who report normal menstrual cycles.

Background: Body composition influences physical fitness (PF) and risk of musculoskeletal injury (MSKI). Assessing the relationship between body fat (BF), PF and MSKI risk in a large diverse military population may provide evidence basis informing health-care policies, practices, and programs for military and civilian populations. Objective: Evaluate validity of expedient methods to estimate BF (e.g., circumference-based equation (CBE) and bioelectrical impedance analysis (BIA)) and investigate relationships between BF and PF with MSKI risk in a large diverse population. Methods: Participants were 1904 active-duty Soldiers (643 F) representing Army demographics sex, race/ethnicity (R/E) and age. PF, defined as most recent Army Combat Fitness Test (ACFT) score and incidence of MSKI were obtained from Army records. BF was determined by dual-energy x-ray absorptiometry (%BFDXA), bioelectrical impedance analysis (%BFBIA), and CBE using a 3-site (Hodgdon, %BFHE) and 1-site (Taylor-McClung, %BFTM) equations. Results were stratified by race and sex, to evaluate differences in accuracy of estimated %BF (weighted root mean squared error from %BFDXA). Associations of BF and PF with MSKI risk were evaluated with logistic regression. Results: CBE and BIA underestimated %BF compared to %BFDXA. %BFBIA differed from %BFDXA overall and by sex. %BFTM underestimation was uniform across both sex and R/E compared to %BFDXA. Mean differences from %BFDXA by sex (M;F) were lower when measured by %BFTM (4.38; 4.59) compared to %BFHE (5.88; 4.39). Individuals had a greater likelihood of MSKI if they failed BF standards (odds ratio 1.32). Scoring ≥540 total on ACFT exhibited a 31% (95% CI: 0.52, 0.92) lower MSKI risk during the following 12 months than those with a lower score. Conclusions: A single-site BF equation (%BFTM) maintained similar accuracy across the Soldier population by sex, age, and R/E. Implementing a PF score threshold in lieu of passing Army BF standards was associated with lower MSKI risk.