A Job Task Analysis of the Physical Demands of Manually Preparing a 4-Person Battle Trench as a Military Defensive Position

Aim: Conduct a Job Task Analysis (JTA) to quantify the physical demands of preparing a defensive position by British Army Ground Close Combat (GCC) roles. Method: Subjective data to describe the demands of preparing a defensive position were gathered from focus groups (n=90) and questionnaires (n=1495). Eight GCC personnel were observed preparing a defensive position which involved digging, lifting, and carrying materials. The oxygen cost of digging was measured using staged reconstructions at slow (12 shovels∙min-1, n=16) and fast (22 shovels∙min-1, n=13) rates. Results: The JTA identified digging trenches, filling sandbags, and shovelling debris as principal tasks of preparing a defensive position. Oxygen cost during the fast-digging rate (27.45 ± 4.93 ml∙kg-1∙min-1) was 26% greater than the slower rate (21.75 ± 2.83 ml∙kg-1∙min-1; p<0.001, d=-1.461). Conclusion: Digging a defensive position was identified by military experts as a critical job-task, with variability in metabolic cost dependent on work rate. Data may inform selection, training, and technology interventions to improve task performance.