Analysis of hip rotation ROM and strength in amateur soccer players: a cross-sectional study

Introduction This study aimed to examine variations in hip rotation range of motion (ROM) and strength when measured at 90° or 0° hip flexion in amateur soccer players, and to assess whether a standardized measurement protocol can be established. Additionally, it assessed the impact of normalizing strength values by body mass and lower leg length, and whether playing position affects hip rotator ROM and strength. Methods A total of 56 amateur soccer players from the Valencian region were tested for maximal voluntary isometric contraction (MVIC) and ROM of hip rotator muscles, measured at both 0° and 90° hip flexion. ROM was measured using a digital inclinometer and strength was assessed using a handheld dynamometer. Statistical analyses included paired samples t -tests, effect size calculations, Pearson's correlation analysis, and one-way ANOVA to examine variations across playing positions. Results Significant differences were found in hip internal rotation (IR) ROM at 90° vs. 0° flexion for both right and left hips ( p = 0.001 and 0.011, respectively). However, the magnitude of these differences was limited, with higher ROM values at 90°, while external rotation (ER) differences were not significant. Strength measurements showed significant increases at 90° compared with 0° for IR and ER in both right and left hips (IR: p < 0.001; ER: p < 0.001 and 0.005, respectively). Normalized strength values also revealed significant differences for both variables across angles ( p < 0.001–0.005). No significant differences were found between ROM and strength values when comparing playing positions. Conclusions Findings support assessing strength in both positions, whereas ROM differences between positions were of limited magnitude and uncertain clinical relevance. These findings underscore the importance of context-specific assessment protocols. Normalizing strength values may not be necessary in this homogeneous population. No position-dependent differences in hip rotator ROM or strength were detected in this sample, suggesting that screening or normative values may not need to be position-specific for amateur male soccer players.