Risk Factors for Training Injuries among British Army Recruits

Military Medicine, Mar 2008 by Blacker, Sam D, Wilkinson, David M, Bilzon, James L J, Rayson, Mark P

ABSTRACT This study aimed to identify risk factors for training injuries resulting in referral to a remedial instructor (RI) or medical discharge (MD) among British Army recruits undertaking initial training. Physical performance and anthropometric data for 11,937 male and 1,480 female recruits were examined as potential risk factors for RI referral and MD, using Cox regression. There was a trend showing that female recruits' MD rates were higher than male recruits' rates (p = 0.096), and RI referral rates were significantly greater for women than for men (p = 0.041). The independent risk factors for MD were 2.4-km run time, ethnicity, and Army training regiment attended (p

INTRODUCTION

Although risk factors for the development of training injuries have been investigated in detail during U.S.,1-9 Australian,10,11 and Norwegian12,13 military training, there are no previously published studies identifying risk factors for injury during current British Army initial training courses. Previously identified risk factors for injury during various military training programs include aerobic fitness,4,5,10,12-16 gender,2,15,16 age,3,6,12 ethnicity,6 smoking,1,5,6,13,17,18 physical activity and exercise before starting training,5,13,17 previous injury before the start of training,18 muscular endurance and strength,4,5,16 flexibility,5 and anthropometric measures.2,3,12,16 These risk factors differ between military training programs and are specific to the populations investigated because of differences in recruit characteristics, training regimens, and environmental factors.

British Army initial training, which is attended by all potential soldiers except for infantry and junior recruits, consists of a 12-week training program, the common military syllabus (recruits) [CMS(R)], and is currently undertaken at three Army training regiments (ATRs). The course teaches military skills through classroom and practical lessons and improves recruits' physical fitness through a progressive, structured, physical training program.

The most recent analysis of training injuries during British Army initial training courses found high rates of overuse injuries (2.4% for men and 11.1% for women).15 Training injuries can result in the loss of training time, causing reductions in physical fitness and specific skills training, which may result in recruits being put back in training or, in cases of severe injury, discharged from the military. This is of high personal cost to individual recruits and financial cost to the military. The aim of this investigation was to quantify injury rates and to identify risk factors for the development of training injuries (all acute and overuse injuries diagnosed by trained medical staff members) that resulted in referral to a remedial instructor (RI) or medical discharge (MD) among British Army recruits undertaking CMS(R).

METHODS

Subjects

Subjects consisted of 13,417 recruits (11,937 male recruits and 1,480 female recruits) who started CMS(R) after January 1, 2003, and completed training before March 1, 2005. Subject characteristics are presented in Table I. Ethics approval was obtained from the School of Sport and Exercise Sciences ethics committee at the University of Birmingham. Subject data were obtained through retrospective analysis of training and medical records. Recruits' names and military numbers were removed to ensure subject anonymity; therefore, written informed consent could not be obtained from individual subjects. Permission to access recruits' training and medical records was granted by Occupational Medicine, Headquarters Army Training and Recruiting Agency.

Data Collection

Data describing recruits' physical characteristics and fitness and strength test results were extracted from the Training, Administration, and Financial Management Information System, which records data on all recruits who enter British Army training. The data set was produced by selecting recruits from the database who had undertaken training at all ATRs that conduct CMS(R), that is, ATR Pirbright, ATR Lichfield, and ATR Winchester. The summary data for each parameter are shown in Table I. Physical characteristics (age, height, body mass, body mass index [BMI], and body fat percentage) were recorded and physical selection testing was conducted by military physical training instructors at one of four recruit selection centers, before the beginning of military training.

The 2.4-km run time was measured when recruits completed a standardized, 2.4-km, outdoor course. The multistage fitness test (MSFT) was conducted in a gymnasium; subjects were required to run 20-m shuttles continuously, at progressively increasing speeds, until they were unable to complete three consecutive shuttles. The durations of the tests were taken as the test scores.

Heaves were performed by hanging from a wooden beam with hands shoulder-width apart and the beam grasped in an underhand grip. From the start position (arms straight), the participants performed as many pull-ups as possible, by raising their chins above the bar and then returning to the start position. The score was recorded as the number of complete pull-ups achieved without rest.