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Updated: Jun 23, 2025
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Evaluating Postural Control and Lower-extremity Muscle Activation in Individuals with Chronic Ankle Instability
Published on: September 18, 2020
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Surface electromyography analysis of ankle flexor and extensor activity under different standing stability levels
Fangchao Wu1, Jiahe Zhang2, Kezhen Yang1
1Department of Physical Medicine and Rehabilitation, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Journal of Orthopaedic Surgery (Hong Kong)
|June 23, 2024
Summary
Single-leg standing and unstable surfaces increase ankle muscle activation and co-contraction. Single-leg stance particularly influences the tibialis anterior and gastrocnemius medial muscles more than two-leg stance.
Area of Science:
- Biomechanics
- Motor Control
- Sports Science
Background:
- Understanding ankle muscle activation is crucial for balance and injury prevention.
- Previous research has explored muscle responses to different stances and surfaces.
- The specific effects of single-leg standing versus both-leg standing on varied surfaces require further investigation.
Purpose of the Study:
- To investigate the electromyographic (sEMG) activation patterns of ankle muscles during single-leg standing (SLS) and both-leg standing (BLS).
- To compare muscle activation and co-contraction on flat ground (FG), soft mat (SM), and BOSU ball (BB) surfaces.
- To determine the influence of stance type and surface stability on the tibialis anterior (TA) and gastrocnemius medial (GM) muscles.
Main Methods:
- Thirty healthy young adults participated in the study.
- Surface electromyography (sEMG) measured tibialis anterior (TA) and gastrocnemius medial (GM) muscle activity during SLS and BLS on FG, SM, and BB.
- Muscle activation was quantified as % maximum voluntary isometric contraction (MVIC%), and co-contraction was assessed using the co-contraction index (CI).
Main Results:
- SLS significantly increased TA, GM activation, and co-contraction index (CI) compared to BLS across all surfaces (except CI on BB).
- Unstable surfaces (BOSU ball) significantly increased TA and GM activation and CI during both SLS and BLS compared to stable surfaces (FG, SM).
- Co-contraction index (CI) during BLS on the BOSU ball was significantly higher than on flat ground and soft mat.
Conclusions:
- Single-leg standing (SLS) and unstable surfaces (BOSU ball) elicit greater ankle muscle activation and co-contraction.
- SLS appears to have a more pronounced effect on ankle muscle activation strategies compared to BLS.
- These findings highlight the importance of unstable surfaces and single-leg balance exercises for enhancing ankle muscle engagement and stability.
