Effects of chronic ankle instability on cutaneous reflex modulation during walking

Area of Science:

• Biomechanics
• Neuroscience
• Sports Medicine

Background:

• Chronic ankle instability (CAI) involves persistent ankle instability after injury and is linked to early osteoarthritis.
• Previous research shows altered cutaneous reflexes in CAI patients when seated.
• It remains unclear if these reflex changes persist during functional activities like walking.

Purpose of the Study:

• To investigate sensorimotor function in CAI by analyzing cutaneous reflex modulation during gait.
• To compare reflex responses between individuals with CAI and uninjured controls during walking.

Main Methods:

• 11 CAI subjects and 11 controls walked at 4 km/h on a treadmill.
• Non-noxious sural nerve stimulation was applied at eight gait cycle points.
• Electromyographic responses of four lower leg muscles were measured and compared between groups.

Main Results:

• Cutaneous reflex responses were similar between groups from late stance to late swing phases.
• Uninjured controls showed significant suppression in medial and lateral gastrocnemius during early stance.
• CAI subjects did not exhibit this suppression, indicating a lack of protective unloading response.

Conclusions:

• Individuals with CAI lack a protective unloading response in the triceps surae during the early stance phase of gait.
• Evaluating cutaneous reflex modulations can help identify neural alterations contributing to CAI functional deficits.
• This research highlights potential sensorimotor impairments during functional activities in CAI.