Inversion and Eversion Strengths in the Weightbearing Ankle of Young Women

Maximum isometric ankle inversion and eversion muscle strengths were measured under full unipedal weightbearing in 20 healthy young adult women. When the women wore a low-top shoe, the mean (standard deviation) maximum external eversion moments resisted with the foot in 0 degrees and 32 degrees of ankle plantar flexion were 24.1 (7.6) and 24.1 (8.1) N x m, respectively, while the corresponding values for maximum inversion moments resisted were 14.7 (6.8) and 17.4 (6.4) N x m, respectively. Both shoe height and ankle plantar flexion affected the overall inversion moment resisted by 17% (P = 0.03) at 0 degrees of ankle plantar flexion to 11.9% (P = 0.003) at 32 degrees of ankle plantar flexion. However, neither shoe height nor ankle plantar flexion significantly affected the maximum eversion moment resisted. Although eversion muscle strength of the young women averaged 39% less than the corresponding value found in young men, the sex difference was not significant when ankle strengths were normalized by body size (body weight x height). Thus, when data from healthy young men and women were averaged, eversion and inversion strengths averaged 1.6% and 2.7%, respectively, of body weight x height.