Seasonal Body Composition Changes in Elite Rugby Players: DXA and Anthropometry-Based Comparison of Backs and Forwards.

Background: Body composition analysis in rugby is necessary for profiling athletes for ideal positioning, the establishment of standards and the development of nutritional and training strategies for improvement. This study aimed to assess the body composition of elite rugby players and examine seasonal variations between backs and forwards using dual-energy X-ray absorptiometry (DXA) and anthropometry. Methods: Thirty-two rugby players (25.97 ± 4.51 years; 93.00 ± 15.39 kg; 181.77 ± 6.27 cm) from First Spanish National league team had their body composition assessed using DXA and anthropometry before and after the season. Results: The main findings indicated that backs exhibited significant increases in total mass, lean mass and fat-free mass, whereas forwards showed and increased only in bone mass. In terms of somatotype, significant changes were observed only in backs, who demonstrated increased mesomorphy and ectomorphy. Within the forwards, front-row players experienced greater increases in LM and FFM compared to other forwards. Conclusions: Rugby players show differences in body composition based on the physical demands of their playing position. These positional differences in body composition are influenced by both training adaptations and genetic predispositions, which ultimately determine the suitability of players for specific roles on the field.