Category
Theoretical Proposal
Description
Context: Lateral ankle sprains (LAS) are a common injury among both the general and athletic populations. Often this injury leads to chronic ankle instability (CAI) or, in some cases, a copers ankle. Copers are defined as individuals with a history of at least 1 LAS that occurred greater than 12 months ago and do not report signs of disability and/or experience episodes of ankle instability since their last ankle injury. Limited research exists to explain the differences between CAI and copers. The focused clinical question is: Do muscle activation patterns differ between individuals with CAI and those classified as copers? Methods: A search was conducted in September 2025 from MEDLine, CINAHL Ultimate, SPORTDiscus, Health Source: Nursing/Academic Edition, and Nursing & Allied Collection. Keywords searched included copers, CAI, muscle activation, LAS, tibialis anterior, and peroneus longus. Twenty-four original studies were retrieved; 17 were removed by title or abstract. Seven articles were assessed for eligibility. Four articles were excluded based on criteria. Three articles were included: one prospective cohort study and two cross sectional, case-control studies. Inclusion criterion were articles written in English, =10 years old, with a coper, CAI, and control group, and assessing tibialis anterior electromyography (EMG) activity. Studies that did not meet the criterion or utilized gait analysis were excluded. EMG was the outcome measure to compare the groups. The CASP checklist was used to determine validity of the selected studies. Results: Lee et al. and Pozzi et al. observed individuals with CAI had greater inversion and altered muscle activation, however performance was not impacted. Karbalaeimahdi et al. and Lee et al. observed that copers demonstrated increased stabilizing muscle activation and preparatory strategies, suggesting compensatory mechanisms that improve balance and reduce re-injury risk. Based on the 3 studies, copers demonstrated greater preparatory activation of the tibialis anterior and peroneus longus muscles compared to those with CAI. Based on the Strength of Recommendation Taxonomy, these articles have a Grade B evidence level. Conclusions: The unique activation pattern observed in copers may explain why they avoid disability or reinjury following a LAS more than individuals with CAI. This phenomenon occurs via preparatory ankle dorsiflexion and eversion, using primarily the tibialis anterior and the peroneus longus muscles to stabilize the joint and prevent unwanted inversion and lateral movements of the ankle. Clinicians should be aware of the differences present between copers and CAI. Further research needs to assess if the utilization of these muscle activation patterns can prevent individuals with a history of LAS from developing CAI.
A Comparison of Muscle Activation Patterns Between Chronic Ankle Instability and Copers Among People with a History of a Lateral Ankle Sprain: A Critically Appraised Topic
Theoretical Proposal
Context: Lateral ankle sprains (LAS) are a common injury among both the general and athletic populations. Often this injury leads to chronic ankle instability (CAI) or, in some cases, a copers ankle. Copers are defined as individuals with a history of at least 1 LAS that occurred greater than 12 months ago and do not report signs of disability and/or experience episodes of ankle instability since their last ankle injury. Limited research exists to explain the differences between CAI and copers. The focused clinical question is: Do muscle activation patterns differ between individuals with CAI and those classified as copers? Methods: A search was conducted in September 2025 from MEDLine, CINAHL Ultimate, SPORTDiscus, Health Source: Nursing/Academic Edition, and Nursing & Allied Collection. Keywords searched included copers, CAI, muscle activation, LAS, tibialis anterior, and peroneus longus. Twenty-four original studies were retrieved; 17 were removed by title or abstract. Seven articles were assessed for eligibility. Four articles were excluded based on criteria. Three articles were included: one prospective cohort study and two cross sectional, case-control studies. Inclusion criterion were articles written in English, =10 years old, with a coper, CAI, and control group, and assessing tibialis anterior electromyography (EMG) activity. Studies that did not meet the criterion or utilized gait analysis were excluded. EMG was the outcome measure to compare the groups. The CASP checklist was used to determine validity of the selected studies. Results: Lee et al. and Pozzi et al. observed individuals with CAI had greater inversion and altered muscle activation, however performance was not impacted. Karbalaeimahdi et al. and Lee et al. observed that copers demonstrated increased stabilizing muscle activation and preparatory strategies, suggesting compensatory mechanisms that improve balance and reduce re-injury risk. Based on the 3 studies, copers demonstrated greater preparatory activation of the tibialis anterior and peroneus longus muscles compared to those with CAI. Based on the Strength of Recommendation Taxonomy, these articles have a Grade B evidence level. Conclusions: The unique activation pattern observed in copers may explain why they avoid disability or reinjury following a LAS more than individuals with CAI. This phenomenon occurs via preparatory ankle dorsiflexion and eversion, using primarily the tibialis anterior and the peroneus longus muscles to stabilize the joint and prevent unwanted inversion and lateral movements of the ankle. Clinicians should be aware of the differences present between copers and CAI. Further research needs to assess if the utilization of these muscle activation patterns can prevent individuals with a history of LAS from developing CAI.
