Applied Ergonomics 110 (2023) 104001 2calculate the independent force requirements of a two-person drag, external factors such as environmental conditions, dragging techniques, specialistclothing/equipmentwornandextraneousvariables(e.g., motivation) will likely influence task completion, and thus necessitate the need for ‘real-world’trials. Therefore, the principal aims of the study were to: 1) quantify and summarise the pulling forces exerted, during a one- and two-person simulated casualty drags in physically active civilian men; and 2) establish whether a one-person 55 kg simulated casualty drag is representative of a two-person 110 kg simulated casu- alty drag. 2.Methods 2.1.Participants Twenty recreationally active men (mean±SD: age: 27±9 years; stature: 1.80±0.05 m; body mass: 87.0±13.7 kg) volunteered to participate in this study. Participants were of similar age, stature and bodymasstothosepreviouslyreportedforUKMilitarySoldiers (Coakley et al., 2019; Vine et al., 2022). The 110 kg individual simulated casualty drag performance was chosen to replicate the current British Army PES requirements (British Army, 2020). The study was conducted in accordance with the Declaration of Helsinki, with ethical approval obtained from the Institution’s Research Ethics Committee. Participants received a comprehensive written and verbal explanation of the pro- cedures,beforeprovidinginformedwrittenconsent.Tominimise musculoskeletal injury risk, ethical approval required participants to have a body mass greater than 60 kg. 2.2.Experimental design Participants attended a single experimental session, wearing sports clothing and trainers. In preparation for the session, participants were required to abstain from strenuous exercise and alcohol 24 h prior, and caffeine 2 h prior. Upon arrival, participant’s stature (213 stadiometer, Seca Ltd, UK), and body mass (837 digital scales, Seca Ltd, UK) was recorded to the nearest 0.01 m and 0.1 kg, respectively. For the purposes of this study a one-person simulated casualty drag refers to an individual participant dragging a single drag bag and a two- person simulated casualty drag refers to two participants working together to drag a single drag bag. During the one-person simulated casualty drag, participants held the looped handles of the drag bag in each hand, with their back facing the direction of travel (i.e., backwards facing). For the two-person simulated casualty drags, participants held one of the drag handles and faced the direction stipulated by the experimenter for the given trial (either forwards facing; FWD [direction of travel] or backwards facing; BWD [towards the drag bag]). All drags were completed using an in-service British Army drag bag (61100-4 casualty drag bag, Indigo Fitness, Nuneaton, UK) with an s-beam load cell (RS 250 kg, Tedea Huntleigh, Cardiff, UK) positioned in line with each drag bag handle (Fig. 1) to measure force data. Data were recorded at 1000 Hz, connected to a mobile data logger (DataLOG MWX8, Bio- metrics Ltd, Newport, UK). For all trials, completion time was recorded to the nearest 0.01 s using a stopwatch. 2.2.1.Experimental session Initially, participants completed a ~5 min self-selected warm-up followed by a self-selected number of familiarisation 55 kg drags (that were not included within subsequent analysis). These drags afforded participants an opportunity to practice technique and ensure they were adequately warmed up prior to the main trials. Previously, research by Foulis et al. (2017) has demonstrated no improvement in simulated casualty drag performance across trials so no further familiarisation was incorporated into the study design. After the warm-up, participants completed up to 12×20 m simu- lated casualty drags to an individual best effort, in the following order: 3 x one-person 55 kg; 1 x one-person 110 kg; 8 x two-person 110 kg drags (4 x FWD, 4 x BWD). The three, one-person 55 kg drags were selected given the anecdotal higher variability associated with the lower mass, whilst the one-person 110 kg drag was collected as these data have not previously been reported. All drags were separated by a minimum of 3 min’rest and conducted using a drag bag on a grassed sports pitch. Trials were performed on a dry, short-cut, grassed area where a 20 m drag lane was measured out. The lane was visually inspected periodically to ensure conditions remained consistent for all trials. In the event of the condition of the lane deteriorating, an adjacent new drag lane was used. Participants completed their trials within a sub-group of five partici- pants and therefore completed each two-person drag iteration (FWD and BWD) with each member of the sub-group. Drag pairings and iteration order were randomly assigned. Prior to the start of each drag, the front of the drag bag was posi- tioned on the start line of the lane and load cells were zeroed whilst lying on the ground. Once completed the participant(s) were instructed to pick up and hold the handle(s) in the required manner for the given trial condition. On the experimenter’s command“ready”, participants were required to remove the slack from the drag bag webbing straps and maintain a constant, but minimal force on the handles. After approxi- mately 3 s, the command“go”was given, and participants were required to complete the 20 m course as quickly as possible (Fig. 2). The completion time was taken when the whole drag bag crossed the finish line. To further minimise musculoskeletal injury risk to participants, trials were stopped if the drag time exceeded 60 s. 2.3.Data analysis Data recordings were subsequently downloaded and analysed using a Fig. 1.Theoretical model for calculating drag performance. Fig. 2.S-beam load cell and drag bag handle set-up during a 110 kg drag. C.A.J. Vine et al.