The impact of a lengthened Australian Army recruit training course on recruit injuries

Abstract

Background: An Army recruit is required to complete a variety of strenuous physical activities during their training. These activities have the potential to cause a range of injuries.

Purpose: The aim of this study was to determine if the length of a recruit-training program influenced injury rates.

Materials and Methods: Data were obtained from 267 Australian Regular Army recruits that attended basic recruit training, completing either the 80-day Australian Recruit Course (ARC) or the 100-day Australian Soldier Course (ASC). Injury prevalence and injury incidence were determined following analysis of reported injury data (Incident report form AC   563).

Results: Injury prevalence for ASC recruits was 17.8% and for ARC recruits 13.9%. Injury incidence for the ASC and ARC were 17.8 injuries/100 soldiers/100 days and 17.4 injuries/100 soldiers/100 days respectively. The majority of injuries for both courses were sprains and strains.

Discussion: ASC had a notably higher prevalence of injuries compared to ARC. However when considered against cohort size and exposure to training, both courses had similar injury incidence rates. This study found much lower prevalence and incidence rates than those reported in previous literature on basic recruit training. Injury types were however consistent with previous    literature.

Conclusions: While potentially appearing to increase reported injuries, longer tactical recruit training programs may not influence the incidence of injuries when cohort size and length of training are considered. The types of injuries suffered by Australian Army recruits undergoing training are commensurate with those of foreign defence services.

Keywords: Recruit training, injury, military training, defence, army

Introduction

Prior to entry into military training courses, recruits must pass psychological, medical and physical screening assessments as well as physical fitness tests.1 These physical fitness tests can differ between course types2 and countries2,3 as well as have different requirements according to gender.2,3 Despite meeting the entry requirements, it has been found that many recruits may be required to participate in training that exceeds their previous training loads, resulting in injuries such as stress fractures, sprains and strains of joints and adjacent  muscles.4

Recruit training courses typically include a variety of physical activities such as weight load marching, obstacle assault courses and general physical training.1, 5 In addition to planned physical training sessions, military recruits are required to briskly walk or march between sessions. In the United States, Naval recruits were found to move an additional 20-25 miles (34-40 km) per week marching around their training area.6 In Australia, Army recruits have been found to march an average of 7.5 km per day (excluding physical training and parade drill.7 Although it was found that this ‘incidental activity’ or ‘movement mileage’ was of benefit to recruits’ physical fitness levels, 6 no research into potential injuries this additional loading may cause has been found in the literature. Considering this, excessive loading has been found to have a negative impact on recruit health and lead to injury.6

One such type of injury is stress fractures. Studies of military programs in the United Kingdom, Israel, and the United States have found that stress fractures sustained during training are the leading form of injury to recruits, with two per cent of male recruits and 12 per cent of female recruits 8, 9 and a gender- combined 7 per cent (approximately) of UK recruits sustaining at least one stress fracture in recent studies.1    These studies identified that the incidence of stress fractures was directly proportional to the training load of recruits, which included the duration and intensity of training programs.1 As  a  result  of this, it was found that stress fracture rates  would peak at the point of maximum training load.1

When encapsulated, the above discussions note relationships between recruit injuries and training loads, the physical requirements of recruit training courses and peak injury periods during recruit training. The aim of this paper was to investigate the potential impacts of changes in the length of army recruit training courses on recruit injury presentation.

Methods

Participants:

Participants were Australian Regular Army recruits that attended basic recruit training at the Army Recruit Training Centre (ARTC), Kapooka in 2013. Data were collected from a total of 267 participants from six platoons completing two training courses, the Australian Recruit Course (ARC), made up of four platoons (n=194 recruits), and the Australian Soldier Course (ASC) made up of two platoons (n=73 recruits). Table 1 illustrates the number of recruits and the gender distribution per course.

All participants were required by the Australian Defence Force to pass their physical fitness assessment prior to commencing their training course.  This pre-enlistment   assessment   consisted of a 20-metre progressive shuttle run assessment (minimum score of level 7.5 for both genders), push- ups (minimum score of 15 repetitions for males and 8 repetitions for females), and sit-ups (minimum score of 25 repetitions for both   genders).

Table 1: Comparison of the number of male, female and total recruits in the ARC and ASC

Data Collection:

Data were recorded during the two different Army recruit training course types.  ARC and ASC, over a one-year period. The ARC was a full time 80-day recruit training course which included basic military and weapons combat training, navigation, drill, advanced field craft and first aid, as well as physical training made up of weight load marching, circuits, obstacle courses, and strength and conditioning. The ASC was a full time 100-day recruit-training course, containing all aspects of the ARC but was designed to have a more gradual increase in load over the first four weeks. Furthermore, the ASC contained additional military field training and an extended field phase.

Recruits were randomly selected for each course with no differences in the recruiting process between the courses. The standards for recruits were the same for each course, with the pre-enlistment requirements for recruits unchanged, e.g. fitness requirements, aptitude and psychological profile. With power set  at 0.8 and an alpha level at 0.05, the required number of recruits per group was 64 (total n=128).

Army Physical Training Instructors (PTI) captured the initial fitness assessment data, being push- ups, sit-ups and shuttle run results.  However, at the time of the study, only pass or fail data were available to researchers as opposed to raw results (repetitions completed or run times). Injury data were collected by the 1 Recruit Training Battalion (RTB) Unit Safety Manager (USM) as part of the training management injury surveillance plan. This data, collected to inform the ADF Work Health, Safety and Compensation Analysis and Reporting process, was captured through the incidence report form (AC563). The incident report form was completed by the injured recruit or activity supervisor, and submitted to Defence Occupational Health and Safety representatives, in this case the USM. The report form data included the types of injuries sustained, how they were sustained, the bodily site of the injury, what activity was being conducted at the time of injury, and the week of training the injury occurred. Depending on the severity of the incident, legislated reporting time frames ranged from 1 to 28 days.10 As more than 28 days had elapsed between completion of the selected courses and data collection, all data were considered to have been captured.

Data Extraction and Analysis:

Nominal rolls for each platoon completing the ARC and ASC were attained from the 1 RTB company clerks. The fitness data from PTIs and injury data from AC563s were then aligned to the nominal rolls. Any discrepancies between injury data and nominal roles (for example, a recruit listed in the injury data but not named in the nominal role) were excluded. Reasons for additional names in AC563 may be as a result of incorrect coding, or recruits who re-entered the training program following recovery from injury. Once all data types were aligned, the data were made non-identifiable and the results aggregated.

Injury prevalence represents the percentage of a population injured at a specific point in time.11, 12 For this study, injury prevalence was determined by the following formula:

Injury Prevalence = (number of reported injuries / number of personnel completing respective course) x 100

Injury incidence is defined as the number of injuries sustained during a specific time period within a given population.11, 12 This number may contain only new injuries, 13 may include a combination of both new and recurrent injuries, 12 or may represent the overall number of injuries sustained.11 For this study the following formula was used to determine the injury incidence:

Injury Incidence = number of injuries / number of recruits completing the respective course / course length in days.

To provide context, these results were then multiplied by 100 to provide an injury incidence per 100 soldiers and then again by 100 to provide a course length of 100 days.

Ethics Approval:

Approval for this study was provided by the Commandant of ARTC with ethics approval provided by the Australian Defence Human Research Ethics Committee and the Bond University Human Research Ethics Committee.

Results

No recruits were excluded from the ASC data, while

23 recruit data sets were excluded from the ARC due to incomplete data entries and/or names not found in nominal rolls. It should be noted that no recruits were returned into the ASC course following injury, while some recruits may have been returned to training into the ARC course, and hence were excluded. During the ASC, a total of 13 recruits were injured (mean age = 26.23 ± 8.9 years). Female recruits comprised 38.5 per cent (n=5) of this injured group. In the ARC cohort, a total of 27 recruits were injured (mean age = 23.11 ± 6.1 years). Thirty three per cent (n=9) of the injured ARC recruits were female. The injury prevalence of each course was found to be 17.8 per cent for ASC recruits and 13.9 per cent for ARC recruits. The injury incidence of the ASC and ARC were 17.8 injuries per 100 soldiers per 100 days and 17.4 injuries per 100 soldiers per 100 days respectively.

Table 2 shows the mechanisms of injuries during both the ASC and ARC. When combining the results of both courses, the top three mechanisms of injury were: the unloading of a weapon due to repetitive biomechanical actions (27 per cent, n=11), running (8 per cent, n=5) and carrying equipment (8 per cent, n=5). The greatest number of injuries in the ASC were caused by unloading of weapons at 34 per cent (n=10) compared to the ARC, where carrying equipment resulted in the most injuries, at 31 per cent (n=4).

Table 2: Mechanisms of sustained injuries during ASC and ARC

As seen in Table 3, the most significant type of injury overall was strains and sprains, with a combined total of 15 injuries. Excluding those injuries that were unidentified or non-identified, the highest number of injuries were sprains and strains in the 80-day training course, with 33.3 per cent (n=9), followed by bone stress injuries/fractures, with 18.5 per cent (n=5). Likewise, the 100-day recruit-training course also found sprains/strains and stress fractures to be the highest form of injuries, with 46.2 per cent (n=6) and 23.1 per cent (n=3) respectively. The smallest number of sustained injuries within both training courses were a dislocation and a blister presenting in each course.

Table 3: Types of injuries sustained during ARC and ASC

Although each Australian training course in the present study ran for different lengths of time, each course began on the Wednesday prior to week one, which was considered week zero, wherein introductory classes and physical training were initiated. As a consequence, injuries were first presented in week zero for the ARC and in week one for the ASC.

The weeks of training in which the reported recruit injuries were sustained are presented in Figure 1. Both courses sustained the most injuries in the final weeks of training and particularly in the last week of their respective course. The 80-day course, the ARC, sustained over half their injuries in the final two weeks (51.8 per cent, n=14), during a field training phase, with the majority of injuries occurring in the final week of training, Week 10 (33.3 per cent: n=9). This finding was similar to the 100-day course, with 38.5 per cent (n=5) of all injuries sustained in the final three weeks of training and the highest number of injuries sustained in the final week of training, Week 13 (23.1 per cent: n=3). It should be noted that the final week for both courses is the recruit’s graduation week and loading is typically very low. As such, injury presentations during this period may be due to field injuries sustained the week prior.

Collectively, the highest anatomical injury sites were the ankle/foot, at 20 per cent (n=8), the back/ torso, 12.5 per cent (n=5), and the lower leg which made up 12.5 per cent (n=5) of overall injuries.  The most common anatomical injury sites were back/ torso (30.7 per cent), ankle/foot (15.4 per cent) and shoulder (15.4 per cent) for the ASC and ankle/foot (22.2 per cent) and lower leg (14.8 per cent) for the ARC.

Discussion

This study aimed to address whether differences in the length of recruit training courses affected the number of injuries that were sustained by recruits. In addition, this study intended to examine any differences between course lengths in injury types, anatomical sites of injuries and the times during the training courses that these injuries occurred.

The ASC course had a notably higher prevalence of injuries when compared to the ARC course (17.8 per cent versus 13.9 per cent). However, when viewed through the lens of cohort sizes and exposure to training, both courses had a similar incidence of injuries. In contrast to previous research, the current study revealed much lower injury prevalence rates than those reported by the Department of Defence,14 Rudzki,15 Havenetidis et al.16 and O’Connor  et  al.17 The Australian Defence Force Health Status Report14 reported an injury incidence rate of 127 per 1000 soldiers per year for the  Australian  Army  program for the financial year  1997/1998,  which  was  found to be 14 per cent less than the average rate of 147 per 100 soldiers per year in 1987 to 1991 in the Australian Army.15 Havenetidis et al.16 reported a recruit injury prevalence of 28.3 per  cent  in  233 male Greek Army recruits over a 7-week time period of  basic  combat  training.  However, O’Connor et al.17 discovered an even higher injury incidence during a 6-week training period of 480 Marine Corp Officer candidates. The overall  cumulative  injury  incidence in their study was 60.7 per cent, with  male  and female cumulative injury incidence of  59.5  and  80 per cent respectively.17 In addition, O’Connor et al.17 claimed injury rates of 3.9 injuries per 1,000 person hours  of  physical training.

Similarly, Havenetidis et al.16 produced  results in which the majority of injuries were reported in which the   majority of injuries were reported training on a 7-week basic training course. However, in contrast to the present study, which showed increased injury rates in the final two to three weeks of training, Havenetidis et al.16 reported a continuous and gradual decrease in injuries and injured recruits towards the final weeks of training.

During the final weeks of training, Australian recruits are sent out on a field exercise and are required to complete a dedicated military skills event in which all aspects of training, pack marching, obstacle and assault courses are completed within a small amount of time. Increased injury rates within the final weeks and particularly the final week of training may be a consequence of this increased training load6 and increased fatigue levels of recruits.18

Conversely, O’Connor et al.17 found their highest injury rates within the second (18.4 per cent) and third (27.3 per cent) week of training, without looking at hours of exposure to training and the third (6.66 per 1,000 person training hours) and final (sixth) (5.28 per 1,000 person training hours) weeks, when the hours of exposure to training were taken into account. Similarly, the present study found the majority of injuries occurred in the final week of training, 33.3 per cent for the ARC (Week 10) and 23.1 per cent for the ASC (Week 13).

The leading types of known injuries were sprains and strains followed by bone stress when injury data were aggregated. Sprains and strains represented 46 per cent (ASC) and 33.3 per cent (ARC) of reported injuries, and stress fractures represented 23.1 per cent (ASC) and 18.5 per cent (ARC)  sustained  over the data collection period. These injury types were also found to be the most common type in studies conducted by Havenetidis et al.16 and O’Connor  et al 17.   Furthermore, the Australian Department of  Defence14 reported 39 per cent of injuries in the financial year 1997/98 were sprains and strains of joints and adjacent muscles with fractures (10 per cent) the second leading injury/illness category.14

The distribution of injuries by anatomical site among injured recruits was similar but not equal to other military populations in previous studies. Similar to the study by O’Connor et al.17 Havenetidis  et al.16 and the Australian Department of Defence14 found the most common injury sites were to the ankle and foot. These sites of injury were also in the top three injury sites in studies by Knapik et al.19 and Ross and Allsopp. Other anatomical sites found to be of significance were the knee, tibia and lower limb in general, all of which were also sites of injury in the present study.

Figure 1: Injuries sustained in individual weeks of training

Limitations:

Two key limitations were noted for this study; limited fitness data and lack of more detailed injury information. Due to data restrictions at the time of the study, only pass/fail data were available for physical fitness assessment results.  However, as all recruits are required to pass this assessment, excessively low fitness levels should have minimal impact on the injuries sustained.20 Additionally, the severity of recruit injuries in the study was unknown, including how much time the recruits required off training, or if indeed they had to be withdrawn from training altogether. As such, while both courses may have had a similar injury incidence, one course may have had injuries which were more severe in nature.

Conclusion

While the ASC had a higher prevalence of injury, when injuries took into account exposure, incidence rates between the courses were virtually identical. When considering the ASC against the ARC, recruits were no more likely to be injured on one course over the other. However due to limited data, any potential differences in injury severity between courses could not be determined. Future research examining injury differences between different course lengths would benefit from the inclusion of fitness data and the quantification of injury severity.