O11
STRESS FRACTURE IN MALE ROYAL MARINES RECRUITS: WORKING TOWARD IDENTIFICATION OF THOSE AT HIGHEST RISK OF INJURY
- Bevilacqua, MRC Lifecourse Epidemiology Centre, University of Southampton, UK
Background
Stress fractures (SF) are common among military recruits, causing significant morbidity, training delays, and costly rehabilitation.
Aims
We aimed to report the prevalence of SFs and identify characteristics associated with SF in male Royal Marines (RM) recruits.
Methods
We studied 1,815 male RM recruits (aged 16-33 years) starting a 32-week training programme between November 2017 and March 2020. Baseline exposures included age, weight, body mass index (BMI), waist circumference, waist-to-height ratio, smoking status, estimated maximum oxygen consumption (VO2max), and physical fitness measures (sit-ups, press-ups, pull-ups). Incident SFs were determined through radiography or MRI. Univariate logistic regression was used to assess associations.
Results
The median age was 21 years. Cardiorespiratory fitness was high (median VO₂max of 52.2 mL/kg/min), and mean BMI was 24.5 kg/m2. Most recruits (85.6%) had healthy central adiposity, and 10.4% were smokers. 102 (5.6%) recruits sustained at least one SF, with the highest rates in those aged 16-18 years (7.2%). The highest quintiles of BMI (odds ratio 0.16, 95% CI 0.06-0.42, p<0.001), weight (0.50, 0.26-0.95, p=0.036), waist circumference (0.40, 0.19-0.83, p=0.014), and waist-to-height ratio (0.37, 0.18-0.78, p=0.009) demonstrated significantly lower odds of SF compared to respective lowest quintiles. No other baseline exposures were associated with SF risk.
Conclusions
SFs were common in Royal Marines recruits, especially those who were less skeletally mature. Higher BMI appeared protective against SF risk, and we hypothesise that greater BMI is likely related to reduced SF risk via greater muscle mass rather than greater adiposity. Further validation in other cohorts is planned.
References:
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Davey T, Lanham-New SA, Shaw AM, Hale B, Cobley R, Berry JL, et al. Low serum 25-hydroxyvitamin D is associated with increased risk of stress fracture during Royal Marine recruit training. Osteoporos Int. 2016;27(1):171-9.
Sanchez-Santos MT, Davey T, Leyland KM, Allsopp AJ, Lanham-New SA, Judge A, et al. Development of a Prediction Model for Stress Fracture During an Intensive Physical Training Program: The Royal Marines Commandos. Orthop J Sports Med. 2017;5(7):2325967117716381.
Sammito S, Hadzic V, Karakolis T, Kelly KR, Proctor SP, Stepens A, et al. Risk factors for musculoskeletal injuries in the military: a qualitative systematic review of the literature from the past two decades and a new prioritizing injury model. Mil Med Res. 2021;8(1):66.
