Aerobic performance and body composition changes during military service

TLDR

The study examined how aerobic performance relates to changes in body composition across BMI categories during 6–12 months of military service. Body composition was assessed by bioelectrical impedance analysis measuring fat mass, fat‑free mass, and visceral fat area, while aerobic capacity was evaluated with the Cooper test at the start and end of service in 945 conscripts. Conscripts improved running distance by 6.8 % overall, with larger gains in overweight and obese groups, and stronger inverse correlations were found between aerobic performance and weight, waist circumference, fat mass, and visceral fat area, indicating that better fitness is linked to greater reductions in body composition metrics, especially among heavier men.

Abstract

To examine the association between aerobic performance and body composition changes by body mass index (BMI).6-12 months' follow-up during military service.Conscripts entering military service in 2005 in Sodankylä Jaeger Brigade (Finland).945 men (19 years, SD 1 years).Height, weight, waist circumference, BMI, and aerobic performance (Cooper test) were recorded. Body composition was measured by bioelectrical impedance analysis (BIA). The measured parameters were fat mass (FM), fat free mass (FFM), and visceral fat area (VFA). All the measurements were performed at the beginning and end of service.On average, the military training period improved the running distance by 6.8% (169 m, p < 0.001) and the improvements were more pronounced in overweight (223.9 m/9.5%, p < 0.001) and obese (273.3 m/13.6%, p < 0.001) conscripts. A strong inverse correlation between aerobic performance and body composition changes was observed, especially for weight (r = -0.305, p < 0.001) and VFA (r = -0.465, p < 0.001). A significant association between aerobic performance and changes in weight (p < 0.001), waist circumference (p < 0.001), FM (p < 0.001), and VFA (p < 0.001) by BMI was detected. The associated decrease in weight, waist circumference, FM, and VFA with improved aerobic performance was more substantial between overweight and obese compared with normal-weight subjects.Favourable changes in body composition are associated with improved aerobic performance during a physical training period such as military service. These findings are pronounced among overweight and obese men and can be applied at the population level in reducing obesity and co-morbidities.