Abstract
Individuals with chronic ankle instability (CAI) have altered muscle activation. However, little is known about the differences in muscle activation of the lower extremity in individuals with bilateral and unilateral CAI. PURPOSE: To investigate differences in muscle activations during single-leg stance in individuals with bilateral and unilateral CAI. METHODS: Sixty participants were divided into 3 groups: 20 individuals with bilateral CAI (bilateral), 20 individuals with unilateral CAI (unilateral), and 20 healthy controls (control). Participants performed 3 trials of single-leg stance while muscle activations were recorded for 10 seconds. During the stance, participants stood with hands crossed on their chest and the opposite leg raised to approximately 45° of knee flexion and 20° of hip flexion. Electromyography (EMG) devices (2,000Hz, Delsys, Boston, MA) were placed on tibialis anterior (TA), peroneus longus, medial gastrocnemius, vastus lateralis, gluteal medius, and gluteal maximus. Reference EMG data were collected for 3 seconds in the standing position before the static balance. EMG data were imported into Visual 3D software and smoothed using a root mean square algorithm (125 ms moving window). The smoothed EMG data were normalized to the smoothed reference EMG data using custom-written algorithms in Matlab. The smoothed EMG signals were averaged over the 10-second period to calculate the integrated EMG (iEMG), which represents both the temporal (task time) and spatial (EMG amplitude) of muscle activity. Muscle activations were analyzed by one-way ANOVA. RESULTS: The bilateral group showed greater integrated electromyography in TA compared to the unilateral (75.05 ± 46.39 vs. 25.59 ± 12.40, p<0.01) and control (75.05 ± 46.39 vs. 44.53 ± 23.46, p<0.01) groups. The unilateral group showed lower iEMG in the TA compared to the control group (25.59 ± 12.40 vs. 44.53 ± 23.46, p<0.01). CONCLUSION: Individuals with bilateral CAI exhibit greater iEMG in the TA during single-leg stance compared to those with unilateral CAI and healthy controls, while those with unilateral CAI show lower TA activation than healthy controls. These findings may be linked to static postural control ability, as the TA is involved in dorsiflexion and inversion movements and plays an important role in maintaining ankle stability.
Recommended Citation
Lee, Tanner; Lee, Hyunwook; Han, Seunguk; Oh, Minsub; and Hopkins, Jon Tyson
(2024)
"Differences in Muscle Activation in Individuals with Bilateral and Unilateral Chronic Ankle Instability Ankle Instability,"
International Journal of Exercise Science: Conference Proceedings: Vol. 14:
Iss.
4, Article 30.
Available at:
https://digitalcommons.wku.edu/ijesab/vol14/iss4/30
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