Neuromuscular Electrical Stimulation Improves Balance Ability In Individuals With Chronic Ankle Instability

PURPOSE: To explore the effect of six weeks peroneal longus neuromuscular electrical stimulation (NMES) on the balance ability in individuals with chronic ankle instability (CAI). METHODS: This study is a single blind randomized controlled trial. Thirty-eight participants with CAI were finally included and randomly assigned to NMES group (males/females:12/7, 22.32 ± 1.89 years) and control group (males/females:12/7, 22.00 ± 1.94 years). Participants in both the NMES and control groups underwent a total of 18 sessions, with each session lasting 20 minutes, three times a week, over the course of six weeks. A symmetrical, biphasic and squared waveform current with a frequency of 20 Hz and a pulse duration of 0.3 ms was used. Sham stimulation was conducted with 0 mA stimulation intensity in the control group. Root Mean Square (RMS), RMS in the medial-lateral direction (RMS-ml), RMS in the anterior-posterior direction (RMS-ap), 95% confidence ellipse area (95%AREA) and Mean Velocity (MV) of the center of pressure (COP) were measured using Kistler force platform (Kistler, 9287BA, Switzerland) during single involved leg standing test with eyes open. Two-way repeated measures ANOVA was used to analyze the main effects of group and time, and their interaction effects on the variables. RESULTS: Significant time and group interaction effects were found in RMS (p = 0.045), RMS-ml (p = 0.008), RMS-ap (p = 0.032), 95%AREA (p = 0.005) and MV (p = 0.005). Post-hoc comparisons revealed that significant between-group differences were found in RMS-ml (NMES:7.06 ± 0.91 mm, control: 8.29 ± 2.45 mm, p < 0.05) and 95%AREA (NMES:843.26 ± 219.76 mm2, control: 1156.64 ± 567.01 mm2, p < 0.05) at week6. Compared with baseline, RMS (pre:12.40 ± 2.01 mm, post:9.84 ± 1.17 mm, p < 0.05), RMS-ml (pre:9.17 ± 1.96 mm, post: 7.06 ± 0.91 mm, p < 0.05), RMS-ap (pre:8.13 ± 1.07 mm, post:6.60 ± 1.14 mm, p < 0.05), 95%AREA (pre:1301.26 ± 371.02 mm2, post:843.26 ± 219.76 mm2, p < 0.05) and MV (pre:16.39 ± 4.47 mm/s, post:13.48 ± 2.76 mm/s, p < 0.05) significantly decreased after interventions in NMES group. CONCLUSION: Six-week of NMES on peroneus longus could improve balance ability in individuals with CAI. This work was supported by the Shandong Province Natural Science Foundation (ZR2020QC091).