This study assessed soldier's physical demands and energy balance during the Section Commanders' Battles Course (SCBC). Forty male soldiers were monitored during the 8-week tactics phase of the SCBC. Energy expenditure was measured using the doubly labeled water method. Cardiovascular strain (heart rate) and physical activity (using triaxial accelerometer) were also monitored. Average sized portions of meals were weighed, with all recipes and meals entered into a dietary analysis program to calculate the calorie content. Energy expenditure averaged 19.6 ± 1.8 MJ · d(-1) in weeks 2 to 3 and 21.3 ± 2.0 MJ · d(-1) in weeks 6 to 7. Soldiers lost 5.1 ± 2.6 kg body mass and body fat percent decreased from 23 ± 4% to 19 ± 5%. This average weight loss equates to an estimated energy deficit of 2.69 MJ · d(-1). The Army provided an estimated 14.0 ± 2.2 MJ · d(-1) in weeks 2 to 3 and 15.7 ± 2.2 MJ · d(-1) in weeks 6 to 7. Although this provision adheres to the minimum requirement of 13.8 MJ · d(-1) set by Army regulations, soldiers were in a theoretical 5.6 MJ · d(-1) energy deficit. The physical demands of SCBC were high, and soldiers were in energy deficit resulting in loss in body mass; primarily attributed to a loss in fat mass.

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.

BACKGROUNDAccelerometers are commonly used to quantify physical activity. There is no accordance regarding the most suitable attachment site. This study assessed the reliability and validity of accelerometer output (PAC) from 2 placements.METHODS26 females (age 20.4 ± 1.3 years, body mass 62.7 ± 6.8 kg) twice performed a 16-minute treadmill protocol comprising 4 stages (4, 5, 8, 10 km·hr(-1)) and oxygen uptake (VO2) was calculated. Participants wore an accelerometer at the hip and lower back. Skinfold thickness was measured at 8 sites. Reliability was assessed using coefficients of variation (CVintra). Interactions between placement, velocity and PAC (counts·5s(-1)) were assessed using analysis of covariance. PAC-VO2 associations were assessed using multiple regression.RESULTSHip and back placements returned similar reliability (CVintra = 3.0% and 2.8% respectively). Hip PAC were higher (P < .01) during walking with no differences observed during running. Indices of adiposity were related to hip PAC. Regression revealed hip and back PAC as significant predictors of VO2. Back PAC was the least variable. Hip skinfold thickness explained 15% additional variance in VO2 to PAC with reduced standard error.CONCLUSIONThe lower back is a more suitable accelerometer placement for young, active females during treadmill exercise.

Strength and reversibility of direction-of-motion stereotypes and response times are presented for different configurations of horizontal, vertical and rotary controls with horizontal, vertical and circular displays. Measures of the strength and reversibility of stereotypes were used to analyse the effects of direction of turn instruction (clockwise/anticlockwise; up/down; left/right), display orientation (North; East; South; West) and hand side (left/right) on movement compatibility. A number of acceptable display/control arrangements were identified for displays in each of the North, East, South and West orientations relative to the operator. For the horizontally moving control, the Worringham and Beringer principle was found to identify display/control arrangements having both high stereotype strength and high reversibility. Vertically moving controls are excellent with vertical displays but poor with horizontal and circular displays. Rotary controls have high stereotype strength and reversibility with both horizontal and circular displays (with the indicator at the 12 o'clock position). Statement of Relevance:Design of display/control arrangements requires a strong relationship between operator's expectancies and the response of a device to control inputs. The present research fills in gaps for stereotypes where data are not available, in particular where the operator is not seated facing a display directly to the front.

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.

The Section Commanders' Battles Course (SCBC) is a 15 week infantry skills course for junior non-commissioned officers, renowned for its high physical demands. PURPOSE: To determine if the energy requirements of the SCBC are commensurate with the energy provision from Army catering. METHODS: Forty male soldiers (age 25 ± 3 yr; stature 176 ±7 cm; body mass 81 ± 10 kg) were monitored for five weeks (weeks 2-3 and 6-8) during the final eight weeks on the tactics phase of SCBC. The doubly labelled water (DLW) method was used to measure the daily energy expenditure (EE) of 30 soldiers, averaged over two separate 10 day periods. Total body water calculations were used to determine body composition at the start and end of the eight weeks. Sample meals were weighed in the cook-house and in the field (container meals). Recipes and meals were entered into a dietary analysis programme (Microdiet, Downlee Systems Ltd, UK) to calculate the energy and macro-nutrient content. RESULTS: Energy expenditure averaged 4693 ± 424 kcal.day-1 in weeks 2-3 and 5094 ± 471 kcal.day-1 in weeks 6-7. Soldiers lost 5.1 ± 2.6 kg body mass and body fat reduced from 23 ± 4 % to 19 ± 5 % over the eight weeks (n=40). Body composition estimated for the 30 soldiers in the DLW sample showed that the majority of weight loss was due to loss of fat mass (4.1 kg) rather than fat free mass (0.8 kg) (n=30). These body composition changes equate to an estimated energy deficit of 644 kcal.day-1. The Army provided soldiers with an estimated 3350 ± 529 kcal.day-1 and 3746 ± 517 kcal.day-1 in weeks 2-3 and 6-7, respectively. Although this provision adheres to the minimum requirement of 3300 kcal.day-1 set by Army regulations, the provision places soldiers in a theoretical energy deficit of 1340 kcal.day-1. Actual energy deficit was lower than this presumably because the soldiers supplemented their Army provisions from other sources. Macro-nutrient content for carbohydrate, protein and fat averaged 50 %, 15 % and 35 % for cookhouse meals, and 52 %, 15 % and 38 % for container meals. CONCLUSION: The EE during SCBC was high and in excess of energy provision. Macro-nutrient content of the meals was not optimal; carbohydrate and protein content should be increased and fat content decreased in meals provided by the Army. This work was conducted by Optimal Performance Limited and funded by the UK Ministry of Defence.

PURPOSE: This prospective cohort study examined injuries and injury risk factors (an essential component of an injury prevention programme) in British Army infantry soldiers. Although several studies have investigated injuries in recruits, no previous studies have followed trained British Army soldiers. METHODS: Participants were 660 soldiers from three British Army infantry battalions. Soldiers completed a questionnaire concerning physical, occupational, lifestyle characteristics (physical activity, alcohol and tobacco use), 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 one year period before operational deployment. An injury was defined as an event in the medical records indicating that the soldier sought medical care due to physical damage to the body (traumatic and overuse events). For each new injury the activity associated with the injury, the body part injured, and the diagnosis were recorded. All continuous variables were converted into categorical variables. Backward stepping Cox regression calculated hazard ratios (HR) and 95 % confidence intervals (CI) to quantify independent risk factors for injury. RESULTS: One or more injury was experienced by 59 % of soldiers, with a new injury diagnosis rate of 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 injury were younger age (17-19 yr [HR=1.0], 20-24 yr [HR=0.71, CI=0.55-0.93], 25-29 yr [HR=0.89, CI=0.66-1.19] and 30-43 yr [HR=0.41, CI=0.27-0.63]), previous lower limb injury (no/yes HR=1.49, CI=1.19-1.87) and previous lower back injury (no/yes HR= 1.30, CI=1.03-1.63). CONCLUSION: Injury rates for British infantry soldiers were lower than those reported for US infantry (range: 101-223 injuries/100 soldier-years). Future efforts should target reducing the incidence of traumatic injuries, especially those related to physical training and/or sports. Funded from the Human Capability Domain of the MoD Scientific Research Programme

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.

BACKGROUND: Body-borne accelerometers are valuable tools for objectively assessing the frequency, duration and intensity of human physical activity. However, the quality of information received from accelerometers is dependent on the reliability and validity of the devices. PURPOSE: To assess the validity and reliability of the 3DNX™ triaxial accelerometer (BioTel Ltd., UK) in a mechanical setting. METHOD: Nine accelerometers were securely attached to the mounting plate of a Multi Axis Shaker Table (MAST) (MAST-9720, Instron Structural Testing Systems Ltd., UK) using double-sided tape. The units were subjected to eight one-minute stages along each measurement axis (X, Y and Z). The testing schedule spanned a range of frequencies and amplitudes resulting in three conditions at 0.5 g, three at 1.0 g and two at 1.5 g. This schedule was repeated on two occasions. All raw accelerometer data were downloaded and imported into a spreadsheet where 5 s epoch accelerometer counts were averaged over each stage. As each stage was one minute long this was typically the mean of ten values after excluding the first and last epochs of each stage. Intra-unit reliability for each axis was assessed using limits of agreement (LoA) and coefficients of variation (CVintra). Inter-unit reliability was assessed using coefficients of variation (CVinter) and Intraclass correlation coefficients (ICC) which were generated from unit mean values and the mean of all units (3DNX_All). Validity was assessed using simple linear regression. RESULTS: The absolute bias ± 95 % LoA were 0.03 (p>0.05) ± 3.28 counts·5 s-1, -0.23 (p>0.05) ±3.44 counts·5 s-1 and -0.28 (p>0.05) ±4.34 counts·5 s-1 for X-, Y-, and Z-axes, respectively. CVintra for all units ranged from 0.1-0.9 %, 0.0-1.0 % and 0.0-0.9 % for X-, Y-, and Z-axes respectively. CVinter ranged from 0.4-1.3 %, 0.3-0.8 % and 0.4-0.7 % for X-, Y- and Z-axes, respectively. The ICCs were 1.0 for all stages in all axes. The regression between 3DNXTM counts·5 s-1 and acceleration (g) for all axes combined (n=432) was y =211.96x (r2 = 0.99, SEE 6 counts·5 s-1). CONCLUSION: The 3DNXTM is a valid and reliable instrument for measuring accelerations in a mechanical setting.

Accelerometers are commonly used to provide estimates of energy expenditure and quantify physical activity patterns during a wide range of free-living activities. PURPOSE: To assess the effect of monitor placement on triaxial accelerometer count magnitude during incremental treadmill exercise. METHOD: Five male and 6 female, recreationally-active subjects (age 22 ± 3 yr; height 173 ± 9 cm; mass 71 ± 11 kg) completed two incremental treadmill protocols separated by no more than five days. The protocol consisted of three 5-minute walking stages (4, 5 and 6 km.h-1), three 5-minute jogging stages (8, 10 and 12 km.h-1) and four 30-second sprints (14, 16, 18 and 20 km.h-1). Each subject wore four 3dNX™ units on an elastic belt; two positioned in the small of the back (lumbar 4-5) and one positioned on each hip (midaxillary line). The sum of the counts from all 3 axes were stored every 5 s. Five-second epoch accelerometer counts were averaged over each stage. The effects of placement (hip and back) and speed, which were considered fixed, and the interaction effects (placement × speed) on count magnitude were tested by ANOVA. RESULTS: Overall there were no significant differences in count magnitude between hip and back placement (p = 0.738). A borderline interaction effect was observed between placement and speed (p = 0.059). Paired t-tests showed significant differences at 4, 5, 8, 10 and 12 km.h-1. Hip placement resulted in higher count magnitude than back placement at 4 and 5 km.h-1, on average 10% and 6% higher respectively. Back placement yielded higher count magnitude than hip placement at 8, 10 and 12 km.h-1, on average 8%, 7% and 3% higher respectively. CONCLUSION: There were small differences in count magnitude when the monitor was worn on the hip and the back. The direction and magnitude of the differences depend on the speed of the treadmill exercise.

To mitigate the physical demands of training and reduce the incidence of injury among female trainees, British Army recruit training was revised and single sex training platoons were implemented in 2006. PURPOSE: To compare the physical demands of the current initial training programme between male and female platoons and to investigate progression of training. METHODS: Thirty male and 30 female recruits (mean ± SD: age 19 ± 2 years; male height 180 ± 7 cm, female 164 ± 6 cm; male mass 73.8 ± 12.9 kg, female 57.2 ± 6.5 kg; estimated VO2max male 45.2 ± 3.5 mL.kg−1min−1, female 38.4 ± 2.6 mL.kg−1min−1) from parallel single sex platoons volunteered to participate. Physical activity was quantified as physical activity counts (PAC) using the 3dNX tri-axial accelerometer (BioTel, Bristol, UK). Cardiovascular strain was quantified as percentage heart rate reserve (%HRR) using heart rate monitors (Polar, Oy, Finland). Data were collected throughout the waking hours in weeks 1, 2, 6, 9, 13 and 14 of the 14 week training programme. RESULTS: PAC during the waking day averaged 148,537 ± 30,189 for males and 131,163 ± 25,097 for females (p<0.001). For females, the average daily PAC for week 1 was lower than for weeks 2 (14%), 6 (23%) and 14 (22%) (p<0.05), and was not different from weeks 9 and 13. For males, the average daily PAC for week 1 was higher than for weeks 2 (13%) and 13 (61%) (p<0.05), and was lower than week 6 (11%) (p<0.05). %HRR during the waking day averaged 31 ± 5 %, and during the working day (08:30- 17:30) averaged 33 ± 5 %; neither index differed (p>0.05) by sex. Time spent in the hard (60-84 %HRR; 34 ± 23 min.day−1) and moderate (40-59 %HRR; 154 ± 76 min) zones did not differ by gender. For females, the average daily %HRR in the working day was the same for all weeks; for males it was higher in week 1 than any other week (p<0.05). CONCLUSION: While males undertook a greater volume of physical activity during initial training than females, the resultant cardiovascular strain was very similar. While the female platoon demonstrated some progression in the amount of physical activity undertaken, the male platoon showed none. This work was sponsored by the UK Ministry of Defence's Research Acquisition Organisation and was conducted by Optimal Performance on behalf of the Haldane- Spearman Consortium.

Accelerometers are commonly used to provide estimates of energy expenditure and quantify physical activity patterns during a wide range of free-living activities. PURPOSE: To assess the validity and reliability of a new triaxial accelerometer (BioTel Ltd., UK) during treadmill exercise, in accordance with ACSM guidelines for light (< 3 METs), moderate (3-6 METs) and vigorous (> 6 METs) activity zones. METHODS: Five male and 7 female, recreationally active subjects (age 22 ± 3 yr; height 173 ± 9 cm; mass 71 ± 11 kg) completed two incremental treadmill protocols separated by no more than five days. The protocol consisted of three 5-minute walking stages (4, 5 and 6 km·h−1), three 5-minute jogging stages (8, 10 and 12 km·h−1) and four 30-second sprints (14, 16, 18 and 20 km·h−1). Each subject wore two accelerometers on an elastic belt positioned in the small of the back. The sum of the counts from all 3 axis was stored every 5 s. Five-second epoch accelerometer counts were averaged over each stage. The rate of oxygen uptake was measured during all walking and jogging stages using the Douglas Bag technique. Reliability was assessed using limits of agreement and accelerometer cut scores were established using simple linear regression. RESULTS: The mean ratio bias ± 95% limits of agreement for between unit (n=240) and within unit (n=240) reliability were 0.4% (p>0.05) ± 5.6% and −0.7% (p>0.05) ± 12.4%, respectively. The regression between accelerometer counts and METs (1 MET = 3.5 ml·kg−1.min−1) was accelerometer counts = 66.8 METs - 84.1 (r2=0.95, SEE 55 counts). Cut scores for ACSM's light, moderate and vigorous activity zones equated to < 116, 116-317 and >317 counts.5 s−1 respectively. CONCLUSIONS: The new triaxial accelerometer provides a valid and reliable estimation of energy expenditure during treadmill exercise. The validity of the accelerometer against free-living energy expenditure (doubly labelled water) remains to be established.