Effect of a Balance Adjustment System on Postural Control in Patients with Chronic Ankle Instability.

Background/Purpose: This study aimed to evaluate how a two-week program using the in-phase mode of a balance adjustment system (the BASYS) affected postural control in participants with chronic ankle instability (CAI). It was hypothesized that the in-phase mode on the BASYS would lead to improved postural control compared with training on a balance disc. Study Design: Randomized control trial. Methods: Twenty participants with CAI were recruited. The participants were divided into two intervention groups: the BASYS (n = 10) and Balance Disc (BD; cushion type, n = 10). All participants underwent six supervised training sessions over a two-week period. Static postural control during single leg standing with closed eyes was assessed for the CAI limb. We collected COP data while participants balanced on the BASYS. The test was performed for 30 sec, and the total trajectory length and 95% ellipse area were calculated. In the assessment of dynamic postural stability, Y-Balance tests-anterior, posteromedial, and posterolateral directions were measured on the CAI limb for all participants and normalized to the individual's leg length. Participants were recorded at three instances: pretraining (Pre), post-training 1 (Post1: after the first training), and post-training 2 (Post2: after the last training). Results: There was an effect on time in the COP total trajectory length of the BASYS group, which was significantly decreased for Post 1 and Post 2 than for the Pre (p = 0.001, 0.0001). Group differences and time-by-group interactions were not observed for either of the Y-balance test reach distances. Conclusions: The study's primary finding was that two weeks of intervention in the in-phase mode on the BASYS improved static postural control in participants with CAI. Level of Evidence: Level Ⅰ, randomized control trial.

Clinical method to assess shoulder strength related to front crawl swimming power in male collegiate swimmers.

[Purpose] Although a correlation has been reported between shoulder strength and maximum swimming power during arm-only swimming, the correlation between shoulder strength and maximum swimming power during front crawl swimming remains unclear. This study aimed to confirm the validity of a clinical assessment method for shoulder strength related to front crawl swimming power. [Participants and Methods] Study participants included 9 healthy male collegiate swimmers. Shoulder strength, including extension and internal rotation torque and swimming power, were measured. [Results] Maximum swimming power was significantly correlated with extension torque in the position of maximum shoulder abduction on the dominant side (r=0.844). No significant correlations were observed between the swimming velocity-to-swimming power ratio and the rate of bilateral differences in extension torque in the position of maximum shoulder abduction. [Conclusion] The extensor strength in the position of maximum shoulder abduction was significantly correlated with the maximum swimming power, suggesting that this assessment method is useful for front crawl swimmers. Notably, measurements on the dominant side may provide useful data that are essential in training to improve front crawl swimming propulsion.

Correlation between isometric shoulder strength and racket velocity during badminton forehand smash movements: study of valid clinical assessment methods.

[Purpose] The purpose of this study was to confirm the correlation between racket velocity during the forehand smash movements with shoulder extensor strength and internal rotator strength in the neutral and abducted positions. [Subjects and Methods] Fourteen collegiate badminton players participated in the study. Measurements were performed shoulder strength, using torque calculated from the upper extremity length and the isometric force, and racket velocity during the forehand smash movements. The shoulder extensor strength and internal rotator strength were measured in the neutral and abducted positions. [Results] The extension torque and internal rotation torque of the shoulder in the neutral position were not significantly correlated with racket velocity. Additionally, correlations between extension torque of the shoulder in the maximum abducted position and racket velocity were insignificant. However, the internal rotation torque of the shoulder in the abducted external rotated position was significantly correlated with racket velocity (r=0.652). [Conclusion] The shoulder internal rotator strength in the abducted external rotated position are suitable measurements for evaluating badminton players.

Relationship between isometric shoulder strength and arms-only swimming power among male collegiate swimmers: study of valid clinical assessment methods.

[Purpose] The purpose of the present study was to confirm the relationships between shoulder strength (extensor strength and internal rotator strength) of the abducted position and swimming power during arm-only swimming. [Subjects and Methods] Fourteen healthy male collegiate swimmers participated in the study. Main measures were shoulder strength (strength using torque that was calculated from the upper extremity length and the isometric force of the abducted position) and swimming power. [Results] Internal rotation torque of the dominant side in the abducted external rotated position (r=0.85) was significantly correlated with maximum swimming power. The rate of bilateral difference in extension torque in the maximum abducted position (r=-0.728) was significantly correlated with the swimming velocity-to-swimming power ratio. [Conclusion] The results of this study suggest that internal rotator strength measurement in the abducted external rotated position and extensor strength measurement in the maximum abducted position are valid assessment methods for swimmers.

Intra- and inter-rater reliability of isometric shoulder extensor and internal rotator strength measurements performed using a hand-held dynamometer.

[Purpose] The purpose of the present study was to establish the intra- and inter-rater reliability of measurement of extensor strength in the maximum shoulder abducted position and internal rotator strength in the 90° abducted and the 90° external rotated position using a hand-held dynamometer. [Subjects and Methods] Twelve healthy volunteers (12 male; mean ± SD: age 19.0 ± 1.1 years) participated in the study. The examiners were two students who had nonclinical experience with a hand-held dynamometer measurement. The examiners and participants were blinded to measurement results by the recorder. Participants in the prone position were instructed to hold the contraction against the ground reaction force, and peak isometric force was recorded using the hand-held dynamometer on the floor. Reliability was determined using intraclass correlation coefficients. [Results] The intra- and inter-rater reliability data were found to be "almost perfect". [Conclusion] This study investigated intra- and inter-rater reliability and reveald high reliability. Thus, the measurement method used in the present study can evaluate muscle strength by a simple measurement technique.

Same-session and between-day intra-rater reliability of hand-held dynamometer measurements of isometric shoulder extensor strength.

[Purpose] The purpose of present study was to establish the same-session and between-day intra-rater reliability of measurements of extensor strength in the maximum abducted position (MABP) using hand-held dynamometer (HHD). [Subjects] Thirteen healthy volunteers (10 male, 3 female; mean ± SD: age 19.8 ± 0.8 y) participated in the study. [Methods] Participants in the prone position with maximum abduction of shoulder were instructed to hold the contraction against the ground reaction force, and peak isometric force was recorded using the HHD on the floor. Participants performed maximum isometric contractions lasting 3 s, with 3 trials in one session. Between-day measurements were performed in 2 sessions separated by a 1-week interval. Intra-rater reliability was determined using intraclass correlation coefficients (ICC). Systematic errors were assessed using Bland-Altman analysis for between-day data. [Results] ICC values for same-session data and between-day data were found to be "almost perfect". Systematic errors not existed and only random error existed. [Conclusion] The measurement method used in this study can easily control for experimental conditions and allow precise measurement because the lack of stabilization and the impact of tester strength are removed. Thus, extensor strength in MABP measurement is beneficial for muscle strength assessment.

Bracing does not improve dynamic stability in chronic ankle instability subjects.

OBJECTIVES: To investigate the effects of an ankle brace on dynamic postural stability, measured with Time to Stabilization (TTS), in subjects with chronic ankle instability (CAI). DESIGN: Two-within (Condition, Side) repeated measures. SETTING: Research laboratory. PARTICIPANTS: Fifteen subjects with unilateral CAI. MAIN OUTCOME MEASURES: Subjects participated in two testing sessions during which a single-limb jump-landing task was performed with one of two conditions: lace-up ankle brace or no ankle brace. Ground reaction forces were used to calculate Resultant Vector TTS (RVTTS). RESULTS: For RVTTS, there were no statistically significant main effects for Side (F(1,14) = 1.005; p = 0.33) or Condition (F(1,14) = 2.48; p = 0.14), as well as no significant interaction effect (F(1,14) = 1.67; p = 0.22). CONCLUSION: While TTS is a useful outcome tool for identifying deficits in subjects with CAI and improvements related to ankle rehabilitation, this measure of dynamic stability does not appear to be sensitive in detecting the influence of the application of an ankle brace in this pathological group. Researchers need to establish what other testing methods will be the best for determining the outcome of the application of an ankle brace in the laboratory setting to coincide with the epidemiology data that support the use of these devices.