The effect of cryotherapy on postural stabilization assessed by standardized horizontal perturbations of a movable platform.

BACKGROUND: Cryotherapy is a frequently used therapy in the acute treatment of sports injuries, although it has possible negative effects on dynamic postural stabilization. RESEARCH QUESTION: What is the effect of cryotherapy on the postural stabilization assessed by imposed platform perturbations? METHODS: Twenty-four healthy participants (15 male, 9 female) performed 2 test sessions (before and after cryotherapy) consisting of 4 trials each. Each trial included 30 s single leg stance (SLS) on both legs and 4 testing blocks (2 for each leg) of 30 s for the dynamic testing. A single testing block comprised 4 perturbations. After the first session, cryotherapy was applied to the right leg by placing it in ice water at a temperature between 10 °C and 12 ° for 20 min. OUTCOME MEASURES: We assessed the Center of Pressure speed (CoPs) and the mean force variation for both static and dynamic tests. Additionally, the Time To Stability (TTS) was calculated for the perturbations. RESULTS: In the static trials there was an interaction between leg and session present for the mean force variation (p = 0.01) with a large η2 of 0.24, which shows higher variation of vertical force after application of the cryotherapy on the right leg. During the dynamic trials we found an interaction between leg and session for the TTS suggesting increase of the TTS due to the cryotherapy (p = 0.04), with a large η2 of 0.17. No interaction effect was present for the CoPs in the mediolateral and anteroposterior direction (p = 0.62 and p = 0.12, respectively). SIGNIFICANCE: Cryotherapy applied to the lower extremity results in a worse postural stabilization when assessed by platform perturbations. This might be the result of an altered balance strategy, due to impaired proprioception from the affected body part. More research is needed to examine the duration of this effect. LEVEL OF EVIDENCE: Level 3, associative study.

Reliability of a novel dynamic test of postural stability in high-level soccer players.

Postural stability of athletes is commonly tested with single-leg stance (SLS) tests. However, for this population, these tests are insufficiently challenging to achieve high sensitivity. Therefore, a new dynamic SLS test based on standardized translational surface perturbations was developed. This study aimed to assess reliability, sensitivity to learning effects, and internal and concurrent validity of this novel test. Healthy soccer players (21 females, 21 males) performed 2 test sessions. Each session consisted of 2 trials. For one trial, the participant performed a 30-seconds, unperturbed SLS on each leg, followed by 12 platform perturbations per leg. Intraclass Correlation Coefficients (ICC) and correlations between outcomes were calculated for the Center of Pressure speed (CoPs) and Time To Stabilization (TTS). ANOVA was used to assess learning effects. CoPs and TTS showed a fair reliability between sessions (ICC = 0.73-0.76). All variables showed improvement over time within and between sessions (all p < 0.01) and were moderately correlated with CoPs during unperturbed SLS (r = 0.39-0.56). Single-leg dynamic postural stability testing through standardized horizontal platform perturbations yielded sufficiently reliable CoPs and TTS outcome measures in soccer players. The moderate correlations with unperturbed SLS support concurrent validity, but also indicates that the new test captures aspects of postural stability that differ from the conventional, unperturbed SLS test.