Differences in Body Composition Between Special Operations Forces and Conventional Military Units: A Cross-Sectional Study.

BACKGROUND: Special Operations Forces (SOF) undergo significantly more rigorous selection and training than conventional military units, which can have an impact on body composition. The aim of this study was to determine whether SOF exhibit distinct body composition characteristics compared to conventional military personnel. METHODS: A total of 500 Belgian male soldiers, aged 20-30 years, participated in this study. Participants were recruited from six military units: 182 noncommissioned officers (NCOs), 85 officers, 122 paratroopers, 32 SOF, 24 physical training instructors (PTIs), and 55 sailors serving on a frigate (Navy personnel). Multifrequency bioelectrical impedance analysis assessed anthropometric measurements. RESULTS: Mean body weight ranged from a minimum of 75.4 (SD 9.4) kg in NCOs to a maximum of 83.2 (SD 12.5) kg in Navy personnel. Body fat percent was lowest in PTI (13.7% [SD 3.6%]) and highest in Navy personnel (19.7% [SD 5.8%]). Fat mass index (FMI) in SOF was comparable to other units, with 3.6 (SD 0.8) kg/m2. Fat-free mass index (FFMI) was lowest for officers, and highest for SOF, at 19.6 (SD 1.4) kg/m2 and 21.0 (SD 0.9) kg/m2, respectively. A low FMI coupled with a high FFMI was most prevalent in SOF with 53.1%. CONCLUSION: SOF demonstrated the highest FFMI, likely as a result of the rigorous selection process, daily physical training, and operational demands. This finding underscores the importance of body composition assessment in evaluating candidates' potential for success in SOF selection.