Exploratory Comparison of Knee Isokinetic and Inspiratory Muscle Performance in Division I Collegiate Women’s Soccer Players: Midfielders Versus Non-Midfielders

Background: Evidence describing position-related physical characteristics in women’s soccer is growing, but positional differences in laboratory measures are inconsistent, and inspiratory muscle performance has rarely been examined alongside lower-extremity dynamometry. This exploratory pilot study compared dominant-leg knee isokinetic and inspiratory muscle outcomes in Division I collegiate women’s soccer midfielders and non-midfielders. Methods: Eleven players (5 midfielders, 6 non-midfielders) completed concentric knee extension/flexion testing at 60, 180, and 300 deg/s and the Test of Incremental Respiratory Endurance assessment. Because of the small sample and number of outcomes, exact two-sided Mann–Whitney U tests were used, rank-biserial correlations described effect magnitude, and Holm-adjusted p-values were examined within exploratory outcome families defined for this revision. Results: Several unadjusted isokinetic comparisons favored non-midfielders. Extension maximal-repetition total work (MRTW) at 60 deg/s was the only comparison with a within-family Holm-adjusted p < 0.05 (exact p = 0.004; Holm-adjusted p = 0.043). A sensitivity analysis using the alternative archived 60-deg/s set preserved the direction and large effect magnitude (U = 1, exact p = 0.009, r_rb = 0.93), supporting consistency of the exploratory signal across sets. Inspiratory outcomes were not statistically different; SMIP was 380.8 +/− 148.1 PTU in midfielders and 495.0 +/− 92.9 PTU in non-midfielders (U = 5, exact p = 0.082; r_rb = 0.67). Conclusions: In this small exploratory sample, non-midfielders tended to demonstrate higher absolute values across selected knee isokinetic outcomes, but most findings did not remain below 0.05 after within-family multiplicity adjustment, and inspiratory outcomes were inconclusive. These results are hypothesis-generating and require confirmation in larger, position-specific cohorts under standardized testing conditions.