Elite football requires a balance between speed, endurance, strength and agility, where body composition influences performance and biomechanics. Each playing position requires specific morphological characteristics, with few studies providing specific values for professional footballers. The body composition of professional footballers was analyzed using dual- energy X-ray absorptiometry (DXA) over two seasons in teams in Italy and England. A total of 92 professional players were evaluated, classified by playing position, and the evolution of their body composition values was analyzed over two seasons. Height was measured, fat mass, total lean mass and lean mass in the lower limbs, and various body composition indices were calculated using these variables. The results show full-backs, wingers and centre forwards have the lowest fat mass values, while centre backs and goalkeepers are characterised by higher total lean mass and lean mass in the lower limbs. During each season, a reduction in fat mass was observed from the pre-season, followed by a recovery to initial values at the end of the season. The influence of body composition on performance and the specificity of positions on the field are noteworthy. It is concluded that body composition varies throughout the season and according to playing position, suggesting the importance of monitoring it to optimize performance. Based on the variables obtained using DXA, we propose the development of specific indices that allow values to be established in this population, facilitating a more accurate interpretation that is adapted to the demands of professional soccer. The study provides useful values for coaches and physical trainers.

KEY WORDS: Fat mass; Lean mass; Elite football; Dual-energy X-ray absorptiometry.