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Ankle eversion torque response to sudden ankle inversion Torque response in unbraced, braced, and pre-activated
Lars Konradsen1, Glenn Peura, Bruce Beynnon
1The Department of Orthopaedic Surgery, Section for Sports Traumatology, Gentofte Hospital, University of Copenhagen, Birkehaven 26, DK-3400 Hillerød, Denmark. lako@gentoftehosp.kbhamt.dk
Summary
Sudden ankle inversion elicits both automatic and voluntary peroneal muscle responses. The main torque response is voluntary, with individual strategies varying in healthy ankles.
Area of Science:
- Biomechanics
- Neuroscience
- Sports Medicine
Background:
- Ankle injuries are common, particularly inversion injuries.
- Understanding the neuromuscular response to sudden inversion is crucial for prevention.
Purpose of the Study:
- To investigate the electromyography (EMG) and torque responses to sudden ankle inversion in healthy subjects.
- To identify different neuromuscular strategies employed during such events.
Main Methods:
- Simultaneous recording of ankle eversion torque and peroneal EMG in 13 young, ankle-stable subjects during sudden ankle inversion.
- Analysis of torque development and EMG onset latencies under different bracing and pre-activation conditions.
Main Results:
- The eversion torque response was bi-phasic, with an early automatic component (30%) and a later voluntary component (70%).
- Bracing and pre-activation significantly reduced torque response time (p<0.02 and p<0.0005, respectively).
- Three distinct voluntary reaction patterns were observed, indicating inter-individual differences in neuromuscular strategies.
Conclusions:
- Ankle stabilization against sudden inversion is not purely automatic; voluntary muscle activation plays a significant role.
- Healthy individuals exhibit varied strategies for managing sudden ankle inversion, suggesting personalized approaches to injury prevention may be beneficial.