Lower limb neuromotor control during perturbed and unperturbed gait conditions in male runners with Achilles tendinopathy: an exploratory analysis

Achilles tendinopathy (AT) is common among runners and typically presents with Achilles tendon pain. Neuromotor alterations have been reported in AT during demanding tasks such as running; however, alterations during functional tasks such as walking remain poorly understood. Such information may be relevant and inform rehabilitation targets. Therefore, this exploratory study investigated lower limb neuromotor control during walking and running in people with AT compared with healthy controls (CO). Twenty-four male runners participated (AT = 12, CO = 12) and completed walking (WALK), perturbed walking (PERTWALK), running (RUN), and perturbed running (PERTRUN) on a custom split-belt treadmill. Lower limb muscle activity was recorded using electromyography to assess activity onset, offset, and duration during unperturbed tasks, and reflex latency and amplitude during perturbed tasks. A MANOVA (α = 0.05) examined group effects (AT/CO). During WALK, AT showed delayed onset of tibialis anterior, peroneus longus, and vastus medialis (p < 0.05). During RUN, gastrocnemius medialis duration was longer, while gluteus maximus onset was delayed and shorter in AT (p < 0.05). During PERTWALK, tibialis anterior reflex latency was delayed in AT (p < 0.05), whereas reflex amplitudes and all PERTRUN outcomes were not significant. These findings indicate potential neuromotor differences in AT.