Fleur E. Horner

Injuries and injury risk factors among British army infantry soldiers during predeployment training

Purpose This prospective cohort study examined injuries and injury risk factors in 660 British Army infantry soldiers during a predeployment training cycle. Methods Soldiers completed a questionnaire concerning physical characteristics, occupational factors, lifestyle characteristics (including physical training time) and previous injury. Direct measurements included height, body mass, sit-ups, push-ups and run time. Electronic medical records were screened for injuries over a 1-year period before operational deployment. Backward-stepping Cox regression calculated HR and 95% CI to quantify independent injury risk factors. Results One or more injuries were experienced by 58.5% of soldiers. The new injury diagnosis rate was 88 injuries/100 person-years. Most injuries involved the lower body (71%), especially the lower back (14%), knee (19%) and ankle (15%). Activities associated with injury included sports (22%), physical training (30%) and military training/work (26%). Traumatic injuries accounted for 83% of all injury diagnoses. Independent risk factors for any injury were younger age (17–19 years (HR 1.0), 20–24 years (HR 0.71, 95% CI 0.55 to 0.93), 25–29 years (HR 0.89, 95% CI 0.66 to 1.19) and 30–43 years (HR 0.41, 95% CI 0.27 to 0.63), previous lower limb injury (yes/no HR 1.49, 95% CI 1.19 to 1.87) and previous lower back injury (yes/no HR 1.30, 95% CI 1.03 to 1.63). Conclusion British infantry injury rates were lower than those reported for US infantry (range 101–223 injuries/100 soldier-years), and younger age and previous injury were identified as independent risk factors. Future efforts should target reducing the incidence of traumatic injuries, especially those related to physical training and/or sports.

Comparison of the physical demands of single-sex training for male and female recruits in the British Army

This study compared the physical demands and progression of basic training for male and female British Army recruits in single-sex platoons. Thirty male and 30 female recruits were monitored for energy expenditure (EE) (doubly labeled water), physical activity (3-dimensional accelerometry) and cardiovascular strain (percent heart rate reserve) during 6 weeks over the 14-week course. First time pass rate was similar for male (60%) and female (57%) recruits. Average daily percent heart rate reserve (female 31 +/- 4%; male 32 +/- 5%), physical activity levels (female 2.2 +/- 0.2; male 2.3 +/- 0.2) and percentage improvements in 2.4-km run time (female 10 +/- 4%; male 10 +/- 5%) were similar for both sexes (p > 0.05), although male recruits had 12% higher physical activity counts (p < 0.01). Although the absolute physical demands of basic training were greater for male recruits, the relative cardiovascular strain experienced was similar between sexes.

Reliability and validity of the 3DNX accelerometer during mechanical and human treadmill exercise testing

Objective:This study aimed to assess the validity and reliability of the 3DNX triaxial accelerometer in a laboratory and mechanical setting.Methods:Experiment 1: A total of 10 units were fixed to a Multi-axis shaker table. A schedule comprising a range of accelerations was repeated on two occasions along each of the three measurement axes. Experiment 2: A total of 11 recreationally active individuals completed a treadmill protocol (4–20 km hr−1) on two occasions. Two 3DNX accelerometers were secured to the lower back, logging data every 5 s. Oxygen uptake was measured using the Douglas Bag technique. Reliability inter- and intra-units were assessed using a combination of limits of agreement (LoA), coefficient of variation (CV) and intra-class correlation coefficient (ICC). Validity was assessed using simple linear regression. All data are expressed in counts per 5 s (counts 5 s−1).Results:Experiment 1: CVintra ranged from 0.0 to 8.9% in all axes. The absolute bias±95% LoA values were all below four counts 5 s−1. CVinter did not rise above 4.5%. ICCs were 1.0 for all stages in all axes. The relationship between 3DNX counts and acceleration yielded an R2 value of 0.99 and a standard error of the estimate (SEE) of six counts 5 s−1. Experiment 2: CVinter ranged from 7.7 to 16.0% for trial 1 and from 7.7 to 16.2% for trial 2. ICCs between units ranged from 0.95 to 1.00 for trial 1 and from 0.90 to 0.99 for trial 2. Mean ratio bias±95% LoA values for intra-unit and inter-unit reliability were −0.7% (P>0.05)±12.4% and 0.4% (P>0.05)±5.6%, respectively. The relationship between [Vdot ]O2 and 3DNX counts for walking and running was linear (R2=0.65, SEE=1.42 ml kg−1 min−1; R2=0.62, SEE=3.63 ml kg−1 min−1).Conclusion:The 3DNX accelerometer is a reliable and valid device for measuring acceleration in a mechanical setting and during human treadmill exercise.

Development of an accelerometer-based multivariate model to predict free-living energy expenditure in a large military cohort

Abstract This study developed a multivariate model to predict free-living energy expenditure (EE) in independent military cohorts. Two hundred and eighty-eight individuals (20.6 ± 3.9 years, 67.9 ± 12.0 kg, 1.71 ± 0.10 m) from 10 cohorts wore accelerometers during observation periods of 7 or 10 days. Accelerometer counts (PAC) were recorded at 1-minute epochs. Total energy expenditure (TEE) and physical activity energy expenditure (PAEE) were derived using the doubly labelled water technique. Data were reduced to n = 155 based on wear-time. Associations between PAC and EE were assessed using allometric modelling. Models were derived using multiple log-linear regression analysis and gender differences assessed using analysis of covariance. In all models PAC, height and body mass were related to TEE (P < 0.01). For models predicting TEE (r 2 = 0.65, SE = 462 kcal · d−1 (13.0%)), PAC explained 4% of the variance. For models predicting PAEE (r 2 = 0.41, SE = 490 kcal · d−1 (32.0%)), PAC accounted for 6% of the variance. Accelerometry increases the accuracy of EE estimation in military populations. However, the unique nature of military life means accurate prediction of individual free-living EE is highly dependent on anthropometric measurements.

Influence of hydration volume and ambient temperature on physiological responses while wearing CBRN protective clothing

This study examined a low (L; 5 ml/kg per h) and high (H, 10 ml/kg per h) rate of fluid replacement in moderate (18°C) and hot (30°C) conditions on physiological responses while wearing personal protective equipment (PPE). PPE included the gas-tight suit (GTS), the powered respirator protective suit (PRPS) and the civil responder 1 (CR1). Relative to the moderate condition, physiological responses were greater in the hot condition. The percentage change in body mass was different (p < 0.05) between L and H in the hot (L vs. H, GTS: −0.83 vs. −0.38%; PRPS: −1.18 vs. −0.71%; CR1: −1.62 vs. −0.57%) and moderate conditions, although in GTS and CR1 body mass increased (L vs. H, GTS: −0.48 vs. 0.06%; PRPS: −0.66 vs. −0.11%; CR1: −0.18 vs. 0.67%). Fluid replacement strategies for PPE should be adjusted for environmental conditions in order to avoid >1% body mass loss and/or net body mass gain. Statement of Relevance:Currently, the UK Emergency Services do not have specific evidence-based fluid replacement guidelines to follow when wearing chemical, biological, radiological and/or nuclear (CBRN) PPE. Although ad libitum fluid replacement is encouraged (when breathing apparatus permits), recommendations from evidence-based findings specific to different PPE and to different environmental conditions are lacking. This study provides novel evidence supporting the need to develop fluid replacement strategies during CBRN deployments in both moderate and hot environmental conditions for CBRN PPE.