Body mass index and physical training-related injuries in military personnel: a systematic review and meta-regression analysis.

Introduction: Discrepancies exist in findings on how varying body mass index (BMI) levels impact physical training-related injuries across different studies. This systematic review and meta-analysis aimed to evaluate the relationship between BMI and physical training-related injuries both qualitatively and quantitatively.

Methods: A comprehensive search of the MEDLINE, Cochrane and EMBASE databases was performed. The study selection followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic review and meta-analysis were conducted using weighted data and a random-effects model. Subgroup analyses were based on gender and military service branches. Heterogeneity among the studies was assessed through the I² statistic, indicating the proportion of total variation in effect size estimates. Funnel plots and Egger's test were employed to assess publication bias.

Results: 33 studies were included in the analysis, with abnormal BMI (underweight, overweight and obesity) identified as a clear risk factor for training-related injuries (overall RR=1.21, 95% CI 1.15 to 1.27; male RR=1.16, 95% CI 1.08 to 1.23; female RR=1.05, 95% CI 1.02 to 1.09). No significant heterogeneity was observed among navy, army and air force personnel (p=0.58), although abnormal BMI remained a notable risk factor in both the army and air force. Meta-regression analysis indicated that the lowest injury risk occurred at a BMI of 23 kg/m². Obese individuals under the age of 27 and underweight individuals over the age of 27 were at high risk. Additionally, the highest injury risk was observed during the first 5 months of military training, with a gradual decline in subsequent months, stabilising by the 12th month.

Conclusion: Findings suggest that abnormal BMI increases the risk of training injuries among military personnel and that this risk varies with age and the duration of training. Emphasis should be placed on risk prevention in the early stages of military training and on enhanced protection for high-risk populations.