Andrew Siddall

Low fitness, low body mass and prior injury predict injury risk during military recruit training: a prospective cohort study in the British Army

Background Injuries sustained by military recruits during initial training impede training progression and military readiness while increasing financial costs. This study investigated training-related injuries and injury risk factors among British Army infantry recruits. Methods Recruits starting infantry training at the British Army Infantry Training Centre between September 2008 and March 2010 were eligible to take part. Information regarding lifestyle behaviours and injury history was collected using the Military Pre-training Questionnaire. Sociodemographic, anthropometric, physical fitness and injury (lower limb and lower back) data were obtained from Army databases. Univariable and multivariable Cox regression models were used to explore the association between time to first training injury and potential risk factors. Results 58% (95% CI 55% to 60%) of 1810 recruits sustained at least 1 injury during training. Overuse injuries were more common than traumatic injuries (65% and 35%, respectively). The lower leg accounted for 81% of all injuries, and non-specific soft tissue damage was the leading diagnosis (55% of all injuries). Injuries resulted in 122 (118 to 126) training days lost per 1000 person-days. Slower 2.4 km run time, low body mass, past injury and shin pain were independently associated with higher risk of any injury. Conclusions There was a high incidence of overuse injuries in British Army recruits undertaking infantry training. Recruits with lower pretraining fitness levels, low body mass and past injuries were at higher risk. Faster 2.4 km run time performance and minimal body mass standards should be considered for physical entry criteria.

Development of role-related minimum cardiorespiratory fitness standards for firefighters and commanders

Abstract A minimum cardiorespiratory fitness standard was derived for firefighters following a metabolic demands analysis. Design and minimal acceptable performance of generic firefighting task simulations (i.e. hose running, casualty evacuation, stair climb, equipment carry, wild-land fire) were endorsed by a panel of operationally experienced experts. Sixty-two UK firefighters completed these tasks wearing a standard protective firefighting ensemble while being monitored for peak steady-state metabolic demand and cardiovascular strain. Four tasks, endorsed as valid operational simulations by ≥90% of participants (excluding wild-land fire; 84%), were deemed to be a sufficiently valid and reliable basis for a fitness standard. These tasks elicited an average peak steady-state metabolic cost of 38.1 ± 7.8 ml kg−1 min−1. It is estimated that healthy adults can sustain the total duration of these tasks (~16 min) at ≤90% maximum oxygen uptake and a cardiorespiratory fitness standard of ≥42.3 ml kg−1 min−1 would be required to sustain work. Practitioner Summary: A cardiorespiratory fitness standard for firefighters of ≥42.3 ml kg−1 min−1 was derived from monitoring minimum acceptable performance of essential tasks. This study supports the implementation of a routine assessment of this fitness standard for all UK operational firefighters, to ensure safe physical preparedness for occupational performance.

Physical employment standards for UK Firefighters:minimum muscular strength and endurance requirements

Objective: The aim of this study was to assess sensitivity and specificity of surrogate physical ability tests as predictors of criterion firefighting task performance and to identify corresponding minimum muscular strength and endurance standards. Methods: Fifty-one (26 male; 25 female) participants completed three criterion tasks (ladder lift, ladder lower, ladder extension) and three corresponding surrogate tests [one-repetition maximum (1RM) seated shoulder press; 1RM seated rope pull-down; repeated 28 kg seated rope pull-down]. Surrogate test standards were calculated that best identified individuals who passed (sensitivity; true positives) and failed (specificity; true negatives) criterion tasks. Results: Best sensitivity/specificity achieved were 1.00/1.00 for a 35 kg seated shoulder press, 0.79/0.92 for a 60 kg rope pull-down, and 0.83/0.93 for 23 repetitions of the 28 kg rope pull-down. Conclusions: These standards represent performance on surrogate tests commensurate with minimum acceptable performance of essential strength-based occupational tasks in UK firefighters.

A task analysis methodology for the development of minimum physical employment standards

Objective: The aim of this study was to develop a systematic task analysis process for determination of minimum acceptable job performance in arduous safety-related occupations. Methods: A task analysis using modifications on established methods was completed in UK firefighters. Subject-matter experts (all male) identified critical, physically arduous tasks generic to all UK firefighters and developed individual, role-specific task simulations. Video footage and blinded voting were used to determine minimum acceptable task performance. Results: Eight tasks were identified in combination with role-specific variations, task simulations suitable for use in a physical demands analysis, and corresponding minimum acceptable performance. Conclusions: The bespoke steps highlighted here allow structured identification of task-specific minimum performance standards and simulations from which physical employment standards could be based. However, including a more divergent expert panel with respect to age, sex, and race would strengthen the applicability of this framework in future practice.

Lifestyle behaviours and perceived well-being in different fire service roles

Background Aspects of the work environment influence employee well-being. However, it is unclear how employee lifestyle behaviours, health characteristics and well-being may differ within a broader occupational sector. Aims To investigate the health characteristics, lifestyle behaviours and well-being of three Fire and Rescue Service (FRS) occupational groups that differ in shift work and occupational demands: operational firefighters (FF), emergency control (EC) and administrative support (AS) workers. Methods Data were obtained via an online survey using previously validated questionnaires to assess health characteristics, lifestyle behaviours and perceived well-being. Differences between groups were explored, controlling for confounding variables, using analysis of covariance (ANCOVA) methods. Effect sizes are reported where appropriate to demonstrate clinical significance. Results Four thousand five hundred and sixty-four FRS personnel volunteered, with 3333 (73%) completing the survey out of a total workforce of 60000 (8%). FF reported the lowest prevalence of chronic medical conditions (10%), compared with AS (21%) and EC (19%) workers. Total physical activity (PA) was 66% higher among FF compared with EC and AS workers. Components of sleep and self-rated health were independent predictors of well-being irrespective of FRS role. Conclusions FF reported the highest levels of PA and highest perceptions of well-being, and the lowest prevalence of obesity and chronic medical conditions, compared with other FRS occupational groups. These findings may be used to inform FRS workplace intervention strategies.

Physical and physiological performance determinants of a firefighting simulation test: Determinants of firefighting performance

Objective: To examine determinants of firefighting simulation test performance. Methods: Sixty-eight (63 male; 5 female) firefighters completed a firefighting simulation (eg, equipment carry, casualty evacuation) previously validated to test occupational fitness among UK firefighters. Multiple linear regression methods were used to determine physiological and physical attributes that best predicted completion time. Results: Mean (±SD) time taken to complete the simulation was 610 (±79) seconds. The prediction model combining absolute cardiorespiratory capacity (L min−1) and fat mass explained the greatest variance in performance and elicited the least random error (R = 0.765, R2 = 0.585, standard error of the estimate [SEE]: ±52 seconds). Higher fitness and lower fat mass were associated with faster performance. Conclusions: Firefighter simulation test performance is associated with absolute cardiorespiratory fitness and fat mass. Fitter and leaner individuals perform the task more quickly. Work-based interventions should enhance these attributes to promote safe and effective operational performance.

Smoking status and physical fitness during initial military training

Background: Habitual smoking is prevalent in military populations, but whether smoking status influences physical fitness development during training is not clear. Aims: We investigated the effect of smoking status on physical fitness parameters during initial British Army Infantry training. Methods: Routine measures of physical fitness (2.4 km run time and maximum number of press ups and sit ups in two minutes) were obtained in 1,182 male recruits (mean ± SD: age 20 ± 3 y, body mass 70.6 ± 9.8 kg, height 1.77 ± 0.07 m; 58% smokers) at weeks 1, 14 and 24 of initial military training. A linear mixed model was used to identify differences in performance between smokers and nonsmokers over time. Results: Non-smokers performed significantly better than smokers in all performance tests (P<0.01), but rates of improvement during training were similar (P>0.05). Run performance improved by 7% in non-smokers (estimated marginal means with 95% confidence limits; 612 (608-616) s to 567 (562-572) s) and 8% in smokers (622 (619-625) s to 571 (568-575) s). Press up performance improved by 18% in non-smokers (48.3 (47.1-49.4) to 57.0 (55.6-58.3)) and 23% in smokers (44.1 (43.2-45.1) to 54.5 (53.3-55.6)) and sit up performance by 15% in non-smokers (57.3 (56.3-58.2) to 66.0 (64.9-67.2)) and 18% in smokers (53.8 (53.0-54.6) to 63.3 (62.3- 64.3)). Conclusions: Smokers exhibited lower muscular and cardiorespiratory endurance performance than non-smokers. Unexpectedly however, no significant differences in improvement in performance indices were demonstrated between smokers and non-smokers during military training.