Can Baseline Recruit Characteristics Predict Actual Injuries Sustained During New Zealand Army Basic Training?

Introduction: Certain army recruits entering basic training may be at heightened risk of injury. It is unknown if risk factors for lower limb injuries could be identified upon entry to basic training for New Zealand Army recruits. This study investigates if personal, lifestyle and physical performance characteristics reported at entry to training could identify recruits who go on to sustain a lower limb musculoskeletal injury during New Zealand Army basic training.

Materials and methods: Recruits' baseline personal (age, sex, and BMI), lifestyle (history of smoking and previous injury) and physical performance characteristics (2.4 km timed run outcome, ankle range of motion using the weight-bearing dorsiflexion lunge test and lower limb dynamic control using the Y Balance Test) were collected at entry to basic training. Backwards stepwise logistic regression analyses were undertaken to determine if baseline variables predicted the occurrence of an injury during basic training and to determine the optimal model of prediction. Significance was set to 0.10. This study was approved by Commander of TRADOC NZDF February 2012 and from Griffith University Human Research Ethics Committee May 2012 (PES/36/11/HREC).

Results: In total 248 recruits, 228 males and 20 females, were eligible to participate in the study. Forty-six (18.5%) recruits had missing data thus, 202 (81.5%) remained for analysis. There were 114 recruits who reported one or more injuries, and 88 recruits reported no injury. Two variables were associated with injury risk in the final model: passing the 2.4 km timed run and Y Balance Test average normalized posterolateral reach for the right limb. This model accurately predicted 60.9% of recruits with 36 correctly assigned as not injured and 87 correctly assigned as injured.

Conclusions: This study identified that 2 physical performance characteristics were associated with lower limb injury in New Zealand Army recruits commencing basic training; not passing the entry 2.4 km timed run, and low right posterolateral Y Balance Test score for lower limb dynamic neuromuscular control. These findings suggest that physical performance screening may be used to identify recruits at high risk of injury entering training so that mitigation measures could be implemented to lower future injury risk.