Investigation of the Operational Effectiveness of ... - Military Medicine

MILITARY MEDICINE, 173, 2:129, 2008

Investigation of the Operational Effectiveness of Hunter Company, Commando Training Centre, Royal Marines Kathleen Munnoch, MSc; Robert S. Bridger, PhD ABSTRACT The aim of the study was to investigate the operational effectiveness of Hunter Company, Commando Training Centre Royal Marines (RM) in rehabilitating injured RM recruits, through the collection of demographic, medical, and performance data for 1 year’s intake of RM recruits (N ⫽ 1,115). Flow models for progression through mainstream training and through Hunter Company were developed. The data were analyzed to determine the week of training in which different injuries occurred and the duration and outcome of rehabilitation. Sixty percent of ex-Hunter Company recruits were successfully returned to mainstream training and graduated successfully. Given that the median number of weeks in training before injury was 24 and the median time taken to recover from an injury was 14 weeks, it is more effective to rehabilitate a recruit in Hunter Company than to discharge him and replace him with a new recruit.

INTRODUCTION Voluntary withdrawal from Royal Marine (RM) training can be predicted by four main variables: the “recruit test 4” (RT4; mechanical comprehension test) score; assault course time; bleep test performance; and age.1 Three of these factors (bleep level, assault course, and RT4) have been combined into a statistical model, known as the “risk zone model,” which has been used for selection purposes.1 Psychological aspects of recruit performance were also investigated leading to the introduction and evaluation of the “coaching initiative” (an initiative to alter the climate of training from “select-out” to “train-in”).2– 4 Although the coaching initiative made a positive impact in mainstream training,5 relatively little work has been done in the area of injury, psychology, and rehabilitation.6 Hunter Company is made up of two discrete troops and is where all injured RM recruits are rehabilitated (in “1 troop” after initial, major injury, moving to “2 troop,” as rehabilitation progresses). Recruits are then either returned to training or discharged. Approximately one in six recruits is injured at some point during the 32-week course and is admitted to Hunter Company for rehabilitation. Thus, the operational effectiveness of Hunter Company represents an integral part of RM training and was studied using a retrospective longitudinal approach to quantify and map the progress of injured recruits. Having already identified factors predictive of recruits opting out of training at their own request (premature voluntary release), the study aimed to investigate the relationship between injury, opting out of training, and factors predictive of training success (or “passing out” of training). Institute of Naval Medicine, Crescent Road, Alverstoke, PO12 2DL, U.K. Reprints: Kathy Munnoch, Institute of Naval Medicine, Crescent Road, Alverstoke, PO12 2 DL; e-mail: [email protected]. This manuscript was received for review in January 2007. The revised manuscript was accepted for publication in July 2007.

MILITARY MEDICINE, Vol. 173, February 2008

AIMS The aims were: 1. To characterize the operational performance of Hunter Company as measured by its success in returning injured recruits to mainstream training. 2. To determine the time taken to rehabilitate recruits according to injury type. 3. To evaluate the training outcomes of injured and noninjured recruits. 4. To investigate predictors of the short-term return to training and long-term outcomes of rehabilitation, such as opting out (leaving) or successfully passing out of training to become a RM.

METHODS: DESIGN, SAMPLE SIZE, AND CONSENT This was a retrospective, longitudinal study. Data were collected from 1,115 (total 1,132) recruits who joined between September 2001 and August 2002. Informed consent to access medical records was obtained according to the requirements of the Data Protection Act of 1998. Subjects were informed of the study and given a 2-week opportunity to opt out. Permission to access databases was obtained from the local and overall data controllers in accordance with the Medical Research Council Guidelines, “Personal Information in Medical Research.”7 The subjects were matched across several databases using name and service number. The collection of data and crossmatching of participants was piloted using information from 20 to 30 individuals to ensure that the data collection for the main study would run smoothly (Table I). Following adequate linking of information to the databases, the subjects’ names and service numbers were removed, thus rendering the data anonymous. Recruits residing in Hunter Company for reasons other than physical injury (e.g., before discharge) were excluded.

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Effectiveness of Hunter Company Commando Training Centre TABLE I. Demographic data

Training outcome data

Discharged unsuitable: 96 (8.6%)

Flow Model 1: A Year in Training Figure 1 depicts the training year from September 2001 to August 2002. Of 1,115 recruits entering training, 56.5% successfully completed training (or “passed out” of training), 5.7% entered Hunter Company after failing a physical test, and 16.2% entered due to injury. Only 1% of all recruits were discharged from Hunter Company for medical reasons, with the remainder being returned to training. The median rehabilitation time in Hunter Company was 14 weeks. Flow Model 2: A Year in Hunter Company Figure 2 depicts the flow of injured recruits through Hunter Company from September 2001 to August 2002. It should be noted that the total pass out rate for recruits having been through Hunter Company was similar (and not significantly different) to that of training in general (60.2% of injured recruits subsequently passed out of training, as opposed to 55.8% of recruits who had never experienced injury of suf-

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Injury: 181 (16.2%)

(Returned to training)

Discharged medical: 20 (1.8%) (direct from mainstream training) Medical Discharge: 11 (1%) Kings Squad: (completed training) 630 (56.5%)

FIGURE 1.

RESULTS Descriptive statistics were generated from the raw data using SPSS (Chicago, Illinois). The data set was split into Hunter Company recruits and non-Hunter Company recruits. The analyses were cross-checked by the Institute of Naval Medicine statistician. Data on 98.5% of the 2001 to 2002 RM intake (N ⫽ 1,115 RM recruits) were analyzed. The mean (SD) age of the sample was 20 years (3.0). The flow diagrams (Figs. 1 and 2) were developed to illustrate the operational effectiveness of Hunter Company.

Failed Physical Test: 63 (5.7%)

Hunter Company (rehabilitation for injury/remedial training required)

Injury data

Opted out of training: 358 (32.1%)

Mainstream Training

Physical data

Surname Forename Service number Original troop Date of birth Age on joining Original joining date RT scores from the Armed Forces Career Office Personal qualities assessment scores from the Armed Forces Career Office Assault course time from the Potential Royal Marines Course Decimal bleep score from Potential Royal Marines Course Height in centimeters (on entry) Body mass in kilograms (on entry) Body mass index (on entry) Initial/primary injury diagnosis Medical officer’s estimated predicted time for recruit to cover Actual time to recover (return to training) Weeks in Hunter Company Subsequent injury information Weeks in training at disposal date Outcome of training

Total entering training: 1132. No. included in the study = 1115 (98.5%).

Non-injured: 871 (78.1%)

Recruitment data

Variables Collected

A flow model depicting a year in training.

ficient severity to require admission to Hunter Company). The rate of recruits opting out of training at their own request (premature voluntary release) was lower than that of the general training flow model (10.5% compared with 32.1% overall), whereas the discharge rate was higher (23.2% compared with 8.6%). Average Weeks in Training According to Outcome Summary descriptive statistics for each outcome category are shown in Table II. The overall number of weeks in mainstream training after allowance for time in Hunter Company was also calculated. The median was 37 weeks. Description of Hunter Company and Non-Hunter Company Recruits Table III compares the characteristics of injured and noninjured recruits. Recovery Time For the purposes of this study, recovery time was defined as the time taken to rehabilitate a recruit from the date of his injury, to the date he returned to training. Table IV shows the average recovery time for the most common injuries. The overall median recovery time was 14.3 weeks. Although stress fracture of the hip appears to take the longest recovery time, this was based on only three individuals. The skew of the data can be seen when comparing the median to the 25th and 75th percentile values. This shows that the data were not


Effectiveness of Hunter Company Commando Training Centre Total entering HC: 181 (100%) Injury Mainstream Training (Ex-Hunter Company Recruits Only)

Opted out of training: 19 (14.3% of once only HC recruits) Discharged unsuitable: 24 (18% of once only HC recruits) Opted out of training: 0 (0% of twice HC recruits)

Discharged unsuitable: 14 (33.3% of twice HC recruits) Opted out of training: 0 (0% of three times HC recruits)

Once in HC: 133 (73.5% of HC total) Returned to training

Medical Discharge: 6 (4.5% of once only HC recruits)

Re-injury Twice in HC: 42 (23.2% of HC total) Returned to training

Medical Discharge: 4 (9.5% of twice HC recruits)

Re-injury Three times in HC: 6 (3.3% of HC total) Returned to training

Medical Discharge: 1 (16.7% of three times HC recruits)

Discharged unsuitable: 4 (66.6% of three times HC recruits) King’s Squad: Completed training Once HC recruits: 84 (63.2% of once only recruits) Twice HC recruits: 24 (57.2% of twice only recruits) Three HC recruits: 1 (16.7% of three times HC recruits)

Total Discharged unsuitable: 42 (23.2% of HC total)

FIGURE 2.

Total opted out of training: 19 (10.5% of HC total)

King’s Squad Completed training: 109 (60.2% of HC total)

Total Medical Discharges from HC:11 (6.1% of HC total)

A flow model depicting throughput of Hunter Company for 1 year.

TABLE II. Average Number of Weeks in Training Corresponding with Outcome (N ⫽ 1,115) Outcome Code

25th Percentile

Median

75th Percentile

n

1. Opted out of training 2. Discharged 3. Medical discharge 4. Completed training

7.6

11.6

18.6

357

23.5 3.0

36.3 6.3

58.0 66.8

96 29

33.6

34.6

40.6

626

normally distributed (a small number of patients took a very long time to recover); hence, the median was calculated rather than the mean. Predicting Injury Comparison of the mean values of Hunter Company with non-Hunter Company revealed significant differences with respect to age. None of the variables measured at the com-


mencement of training and listed in Table III were found to predict injury. Only smoking on entry to the training course was found to predict injury (RR ⫽ 1.7). Predicting Outcome Table V shows the average number of weeks taken by exHunter recruits and non-Hunter recruits for each possible outcome of training. ␹2 analysis using the dichotomous outcome of pass or fail showed no significant association between the proportions passing out and admission to Hunter Company (␹2 ⫽ 1.2, p ⫽ 0.15). Predicting Recovery Time Only age was positively, significantly associated with actual recovery time (r ⫽ 0.13, p ⫽ 0.05). Smoking did not influence recovery time (t ⫽ ⫺0.53, p ⫽ 0.6). DISCUSSION The aim of this study was to investigate the operational effectiveness of Hunter Company in terms of tangible out-

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Effectiveness of Hunter Company Commando Training Centre TABLE III.

Description of Hunter Company and Non-Hunter Company Recruits Non-Hunter Company

Age on joining (years) RT1: reasoning RT2: numeracy RT3: literacy RT4: mechanical comprehension RT combined total Personal qualities assessment scorea Personal qualities assessment gradea Height (cm) Weight (kg) Body mass index Risk zone score

Hunter Company

Mean

SD

n

Mean

SD

n

19.6 20.7 19.1 18.6 18.6 77.0 27.0 1.9 177.7 73.5 23.3 4.7

2.9 4.5 5.4 5.0 4.3 14.9 2.9 0.7 6.3 8.1 2.2 1.6

934 898 898 898 898 898 896 893 869 912 864 919

20.1 21.0 20.3 18.6 18.8 78.8 27.0 1.9 176.8 73.5 23.4 4.4

3.0 4.6 5.6 5.0 4.2 15.2 2.9 0.8 6.1 9.1 2.5 1.8

181 173 173 173 173 173 173 173 171 177 171 177

a

Personal qualities assessment: an interview-based score on the qualities of a recruit. The personal qualities assessment is recorded as a score and a grade. Both were used in the analysis for this study.

TABLE IV.

Recovery Time in Weeks for the Five Most Common Injuries, with Stress Fractures Divided into Subgroups

Injury

n

25th Percentile

Median

75th Percentile

95% Confidence Interval

Stress no. mt Stress no. tib Stress no.: non-specified Stress no. fib Stress no. hip Knee injury Fracture: other Ankle injury Soft tissue injury

26 19 13 5 3 36 18 17 16

11.5 19.6 7.7 6.0 25.6 15.3 5.6 8.6 13.4

14.9 21.4 17.6 11.6 34.5 18.8 14.0 15.6 17.9

19.3 22.6 25.6 18.6 43.4 30.0 32.4 16.9 23.6

18.69–13.73 18.90–28.46 12.00–22.18 2.56–22.44 20.25–48.75 14.19–32.24 11.35–27.19 9.06–16.16 13.71–27.27

TABLE V.

Outcome of Ex-Hunter Company and Non-Hunter Company in Weeks Non-Hunter Company, N ⫽ 1,115

Hunter Company, N ⫽ 180

Outcome Code

25th Percentile

Median

75th Percentile

n

25th Percentile

Median

75th Percentile

n

Opted out of training Discharged Medical discharge Completed training

7.6 7.3 2.6 33.6

11.6 24.3 4.4 34.6

18.4 34.7 7.3 35.6

339 54 20 521

11.6 47.3 43.0 52.6

21.4 57.1 94.4 58.6

25.4 68.1 113.1 72.5

19 42 11 109

comes such as: percentage pass outs, time in training, and time in Hunter Company. Investigation of the cost of rehabilitation in relation to total training costs was beyond the scope of this report. Operational Effectiveness Approximately one in six recruits were admitted to Hunter Company due to injury. Approximately two-thirds of these subsequently successfully completed and passed out of training. Injured recruits transferred to Hunter Company were as likely to succeed as non-Hunter Company recruits. However, the percentage of recruits passing out of training dropped greatly following multiple reinjury (although the numbers admitted three times were small). The average recovery time in Hunter Company (14 weeks) was less than the average number of weeks in training before

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injury (24 weeks). It is more effective to rehabilitate an injured recruit than to discharge him and replace him with a new recruit and incur the loss of investment in training before the injury. Recruits typically return to training at the point at which they left it due to the injury, the main difference being that parts of the training that are not physically stressful continue during rehabilitation. In addition, the median length of mainstream training for injured recruits was 37 weeks. This did not differ significantly from the 35-week training course completed by non-Hunter Company recruits. Injury The median week of training in which recruits acquired an injury was week 21. This is probably due to the onset of the weight-bearing battle physical tests phase of training and


Effectiveness of Hunter Company Commando Training Centre

therefore the increased physical workload. Of the total injuries, the majority were metatarsal stress fractures. The number of discharges from ex-Hunter Company recruits appears high and the number of opt-outs appears low in comparison to mainstream training recruits. This probably reflects the number of recruits who become reinjured so severely that they no longer wish to persevere, and the number of recruits who wished to withdraw after leaving Hunter Company but were discharged for “administrative” reasons instead. CONCLUSIONS There is evidence that the current rehabilitation system for RM training is operationally effective: 1. The proportion of recruits who successfully passed out of training following rehabilitation was the same as that for mainstream training. 2. The median time in training before injury was 24 weeks and the median time to rehabilitate and return to training was 14 weeks. Therefore, it is more effective to rehabilitate recruits than discharge them and recruit afresh. 3. The median training time for recruits to complete training was 59 weeks for those who had been through Hunter Company and 35 for those who had not. However, the net training time for Hunter Company recruits was no different to non-Hunter Company recruits. The operational effectiveness of the rehabilitation system is likely to be due, in part, to the fact that, apart from having been injured, recruits undergoing rehabilitation in Hunter


Company were no different from uninjured recruits with respect to any of the demographic, physiological, or psychological factors that are known to predict training success in RM recruit training. The only variable in the data set that distinguished injured and noninjured recruits was smoking at the start of training. In terms of the risk zone model used to predict training success, Hunter Company recruits were no different from their uninjured counterparts. ACKNOWLEDGMENTS We thank management and staff at the Commando Training Centre, Royal Marines for their support for this project.

REFERENCES 1. Allsopp AJ, Shariff A: Survival of the fittest. J R Nav Med Serv 2004; 90: 117–24. 2. Hardy L, Jones G, Shariff A, Allsopp A: A Review of the Psychological Aspects of Royal Marine Recruit Training. Unpublished MoD Report. London, U.K., MoD, 2000. 3. Jones H, Bridger R: Preliminary Investigation of RT4 Related Attrition in RM Recruit Training. Unpublished MoD Report. London, U.K., MoD, 2001. 4. Munnoch K, Pethybridge RJ, Bridger RS: An Investigation into the Relationship between Recruit Test 4 Scores and Mechanical Comprehension Dependent Tasks. Unpublished MoD Report. London, U.K., MoD, 2002. 5. Hardy L, Shariff A, Munnoch K, Allsopp AJ: Can Leadership Development Positively Influence the Psychological Environment of Military Recruit Training: An Interim Evaluation of the Royal Marines Coaching Advisory Team Leadership Initiative. Unpublished MoD Report. London, U.K., MoD, 2004. 6. Pargman D (editor): Psychological Bases of Sports Injuries. Morgantown, WV, Fitness Information Technology, Inc., 1993. 7. MRC Guidelines: Personal Information in Medical Research. London, U.K., MRC, 2000.

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