Analysis of selected variables in body composition, upper limb strength, and resting energy expenditure among youth soccer players: insights based on field position

The study aimed to determine and compare selected variables of body composition, upper limb strength, and resting energy expenditure from the perspective of field position in youth soccer players. The study group consisted of 189 boys aged 9 to 19 years ( x¯ = 14.7 ± 2.6 years) from the Sports Championship Schools. Body composition was determined using dual-energy X-ray absorptiometry (DXA), and resting energy expenditure (kcal/day) was measured using a Cosmed Quark RMR indirect calorimeter. Muscle strength was assessed using a handgrip dynamometer to measure grip strength. We studied 189 boys (mean body mass 58.4 ± 16.1 kg; mean height 166.9 ± 14.5 cm) divided by field position: attackers (n = 43), defenders (n = 70), goalkeepers (n = 21), and midfielders (n = 55). Significant between-position differences were observed in age, body mass, height, body mass index (BMI), grip strength (GS), lean mass, fat mass, bone mineral content (BMC), bone mineral density (BMD), and resting energy expenditure (REE). Body mass differed between attackers and goalkeepers (51.3 vs. 73.3 kg) and defenders and goalkeepers (58.7 vs. 73.3 kg). Goalkeepers had the highest body mass. REE measured by indirect calorimetry differed between attackers and goalkeepers (1,729 vs. 2,088 kcal/day). These results allow for determining favorable parameters for each position on the field for young football players.