Effects of focal ankle joint cooling on unipedal static balance in individuals with and without chronic ankle instability

Application of cryotherapy over an injured joint has been shown to improve muscle function, yet it is unknown how ankle cryotherapy affects postural control. Our purpose was to determine the effects of a 20-min focal ankle joint cooling on unipedal static stance in individuals with and without chronic ankle instability (CAI). Fifteen young subjects with CAI (9 males, 6 females) and 15 healthy gender-matched controls participated. All subjects underwent two intervention sessions on different days in which they had a 1.5L plastic bag filled with either crushed ice (active treatment) or candy corn (sham) applied to the ankle. Unipedal stance with eyes closed for 10s were assessed with a forceplate before and after each intervention. Center of pressure (COP) data were used to compute 10 specific dependent measures including velocity, area, standard deviation (SD), and percent range of COP excursions, and mean and SD of time-to-boundary (TTB) minima in the anterior-posterior (AP) and mediolateral directions. For each measure a three-way (Group-Intervention-Time) repeated ANOVAs found no significant interactions and main effects involving intervention (all Ps > 0.05). There were group main effects found for mean velocity (F(1,28) = 6.46, P = .017), area (F(1,28) = 12.83, P = .001), and mean of TTB minima in the AP direction (F(1,28) = 5.19, P = .031) indicating that the CAI group demonstrated greater postural instability compared to the healthy group. Postural control of unipedal stance was not significantly altered following focal ankle joint cooling in groups both with and without CAI. Ankle joint cryotherapy was neither beneficial nor harmful to single leg balance.