Dynamic electromyography (EMG) of the extrinsic muscles of the ankle is used more and more frequently to assist in the planning of tendon transfers in children with equinovarus deformities. Since these children walk at low speeds (1 to 4km/h), and since walking speed modifies the EMG-time pattern, the clinical investigator must be able to differentiate EMG modifications due to pathology versus those due to slow walking speed. The aim of this work was to study the effect of walking speed on the EMG-time pattern of the extrinsic ankle muscles in healthy children between 4 and 11 years of age. This pattern was found to change significantly with speed of progression but is independent of growth over this age range. A nomograph of EMG timing, taking into account walking speed, is proposed for clinical gait analysis.
