WHAT BEST PROTECTS THE INVERTED WEIGHTBEARING ANKLE AGAINST FURTHER INVERSION - EVERTOR MUSCLE STRENGTH COMPARES FAVORABLY WITH SHOE HEIGHT, ATHLETIC TAPE, AND 3 ORTHOSES

We measured the maximal isometric eversion moment developed under full weightbearing in 20 healthy adult men (age, 24.4 +/- 3.4 years, mean +/- SD) with their ankles in 15 degrees of inversion. Tests were perfo rmed at both 0 degrees and 32 degrees of ankle plantar flexion in low- and in three-quarter-top shoes with and without adhesive athletic tap e or one of three proprietary ankle orthoses. At 0 degrees of ankle pl antar flexion, the mean maximal voluntary resistance of the unprotecte d ankle to an inversion moment was 50 +/- 8 N-m; this increased by an average of 12% (or 6 N-m) when the subject wore a three-quarter-top ba sketball shoe, The maximal voluntary resistances to inversion moments developed with the ankles further protected by athletic tape or any of three orthoses were not significantly different, Biomechanical calcul ations suggest that at 15'' of inversion the fully active ankle everto r muscles isometrically developed a moment up to six times larger than that developed when an athlete wears a three-quarter-top shoe alone a nd more than three times larger than that developed passively when the athlete has tape or an orthosis worn inside a three-quarter-top shoe, We conclude that fully activated and strong ankle evertor muscles are the best protection for a near-maxima[ly inverted ankle at footstrike .