Field Position-Related Variations in Body Mass, Postural Control, and Isokinetic Strength in Portuguese Professional...

Background: Combining body composition, dynamic postural control, and isokinetic strength allows for a comprehensive physical and functional assessment of football players across specific playing positions. The aim of this study was to analyze the field position-related variations in the physical and functional profiles of male football players. Methods: A convenience sample of 23 professional male football players from a Portuguese second league team, aged 18 to 32 years (23.83 ± 3.77 years), participated in the present study. Players from five field positions (central backs, central midfielders, wide midfielders, and forwards) were assessed for body composition, dynamic postural control, and isokinetic lower limb strength. Body composition was assessed by bioelectrical impedance; composite scores for postural control in the right and left limbs were obtained through the Y-Balance test lower quarter (YBT-LQ). Peak torque (PT) during lower limb flexion and extension was measured using an isokinetic dynamometer chair. Results: Significant differences were found only in peak torque of the right extensors [H (4) = 9.84, p = 0.043, η² = 0.37)], whereas no significant differences emerged in body mass, dynamic balance scores, left-side extension and flexion, or hamstring-to-quadriceps (H:Q) strength ratios. Post hoc analysis using Mann-Whitney U tests with Holm correction did not confirm pairwise differences between positions. The correlation analysis revealed mainly moderate-to-strong associations between symmetrical measures (composite YBT-LQ right and left, PT extension right and left), as well as between anthropometric and strength variables, but without consistent position-specific patterns. Conclusions: Overall, the study provides valuable insights into the physical attributes of professional football players, highlighting the general similarity of profiles across positions and suggesting that individualized training approaches may still be beneficial to optimizing performance and reduce injury risk. Future studies should extend the analysis to larger cohorts across different professional Portuguese football teams and competitions.