Sex-Related Hip Strength Measures Among Professional Soccer Players.

TLDR: Findings provide baseline pre-season normative data for professional soccer athletes and indicate that strength differences can be expected among different sexes, but are attenuated with attention to body mass.

Abstract: Lower-extremity musculoskeletal injuries in soccer are common among sexes. However, it remains unknown whether differences between sexes exist with regard to absolute or relative hip strength and how these differences may relate to injury. In the current study, we performed a retrospective cross-sectional analysis of pre-season data from male ([male sign]n = 21) and female ([female sign]n = 19) professional United States soccer organizations. Two years of pre-season data were collected for peak strength of lower extremity and hip musculature (no duplicates used). A 2 x 2 multivariate analysis of variance was used to detect differences in hip strength between sexes and dominant compared with nondominant legs. For all significant multivariate effects indicated by Wilks lambda and follow-up univariate analysis, a Tukey's post hoc test was used for pairwise univariate comparisons. A 2-tailed independent-samples T-test was used for comparison of height, body mass, body mass index (BMI), mean leg length, and strength ratios between dominant and nondominant limbs between sexes. Type I error was set at [alpha] = 0.05 for all analyses. Height ([male sign]183.1 +/- 6.8 cm, [female sign]170.0 +/- 5.5 cm), body mass ([male sign]79.0 +/- 8.7 kg, [female sign]65.1 +/- 5.6 kg), BMI ([male sign]23.5 +/- 1.3 kg[middle dot]m-2, [female sign]22.5 +/- 1.4 kg[middle dot]m-2), and mean leg length ([male sign]95.5 +/- 4.34 cm, [female sign] 88.3 +/- 3.24 cm) differed between groups (p < 0.05). Sex differences (p < 0.05) were also found for hip abduction (dominant [male sign]19.5 +/- 3.6 kg, [female sign]17.3 +/- 2.2 kg; nondominant [male sign]18.5 +/- 3.7 kg, [female sign]16.0 +/- 2.3 kg), adduction (dominant [male sign]19.8 +/- 3.0 kg, [female sign]16.7 +/- 2.3 kg; nondominant [male sign]20.1 +/- 2.9 kg, [female sign]17.6 +/- 2.9 kg), external rotation (dominant [male sign]21.7 +/- 3.4 kg, [female sign]17.7 +/- 2.4 kg; nondominant [male sign]21.6 +/- 3.9 kg, [female sign]16.8 +/- 2.1 kg), and dominant hamstring strength ([male sign]27.9 +/- 6.5 kg, [female sign]23.0 +/- 4.9 kg). The ratio of hip internal to external rotation strength differed in the nondominant leg ([male sign]1.1 +/- 0.2, [female sign]0.9 +/- 0.2, p < 0.05). No significant differences were found between males and females when measures were normalized to body mass. These findings provide baseline pre-season normative data for professional soccer athletes and indicate that strength differences can be expected among different sexes, but are attenuated with attention to body mass. Further research should indicate how pre-season strength measures relate to injury.