"Knees Out" or "Knees In"? Volitional Lateral vs. Medial Hip Rotation During Barbell Squats.
Level 3 - non-randomized controlled study
Controlled within-subject laboratory biomechanical study
PubMed 38416444 · doi:10.1519/JSC.0000000000004655
What was done
Thirty-two individuals (14 males, 18 females) performed barbell squats under three conditions: their normal technique, volitional medial hip rotation, and volitional lateral hip rotation. Hip net joint moments (NJM) were calculated from 3-dimensional motion capture and force platform measurements. Statistical comparisons used omnibus tests (alpha = 0.05) with Bonferroni correction for pairwise comparisons (alpha = 0.0056).
What was found
Normal squats required hip extensor, adductor, and lateral rotator NJM. Relative to normal squats: - Lateral rotation squats showed significantly smaller hip extensor (p = 0.002) and lateral rotator (p < 0.001) NJM, and larger hip adductor (p < 0.001) NJM. - Medial rotation squats showed significantly smaller hip extensor (p = 0.002) and adductor (p < 0.001) NJM, and larger hip lateral rotator (p < 0.001) NJM. Numerical values for the joint moments and standard deviations were not reported in the abstract.
Why it matters
Altering knee flare changes hip frontal and transverse plane moments, suggesting that "knees out" squats place greater demands on hip adductors while "knees in" squats increase demands on hip lateral rotators.
Limits
Exact numerical moment values, effect sizes, and squat load percentages are absent from the abstract. The study only measured acute joint kinetics in 32 participants without direct electromyography, meaning actual muscle activation and long-term training adaptations were not assessed.