Effects of Wrist Support Types on Grip Strength, Stability, Muscle Fatigue, and Muscle Activity During Static and Dynamic Functional Tasks

Abstract

Background

Knee orthoses are widely used to provide external support and potentially modify proprioceptive and postural control mechanisms. However, the immediate effects of a figure-of-eight patellar brace on knee muscle strength, joint range of motion, and postural control in healthy adolescents remain unclear. This study investigated the acute effects of a figure-of-eight patellar brace on knee function and postural stability in healthy high school students.

Methods

Six healthy high school students aged 16–18 years, including three males and three females, participated in this study. Knee extension and flexion muscle strength were assessed using a handheld dynamometer, and knee extension and flexion range of motion (ROM) were measured using a digital goniometer. Postural control was evaluated during a 30-second single-leg stance using a pressure-distribution platform. Mediolateral, anteroposterior, and total postural sway were recorded. All measurements were performed before and immediately after application of a figure-of-eight patellar brace. Pre- and post-brace measurements were compared using paired-samples t-tests, and Cohen's d was calculated to estimate the magnitude of the changes.

Results

No statistically significant differences were observed in any outcome following brace application. Knee extension strength decreased from 17.9 ± 3.30 to 16.8 ± 3.43 (p = 0.578, d = 0.33), whereas knee flexion strength decreased from 17.4 ± 7.26 to 16.8 ± 7.19 (p = 0.876, d = 0.09). Knee extension ROM decreased from 169.2 ± 13.20° to 166.7 ± 8.16° (p = 0.701, d = 0.23), while knee flexion ROM increased from 79.2 ± 15.63° to 81.7 ± 12.91° (p = 0.769, d = −0.17). Mediolateral sway decreased from 174.4 ± 37.72 to 157.1 ± 24.78 (p = 0.370, d = 0.54), representing the largest effect size among the assessed variables. Anteroposterior sway showed minimal change (218.1 ± 52.97 vs. 217.2 ± 46.81; p = 0.974, d = 0.02), while total sway decreased from 308.3 ± 64.62 to 294.2 ± 49.88 (p = 0.680, d = 0.25).

Conclusions

A figure-of-eight patellar brace did not produce statistically significant acute changes in knee muscle strength, knee ROM, or postural sway in healthy high school students. However, the moderate effect size observed for mediolateral sway suggests a potential direction-specific influence of the brace on frontal-plane postural control. Given the small sample size and absence of a control condition, this finding should be considered preliminary. Further studies with larger samples and direct assessments of proprioception and neuromuscular activation are warranted to clarify the sensorimotor effects of figure-of-eight patellar bracing.