Introduction
JENSEN
Human gait is highly adaptable allowing over-ground bipedal progression to remain effective even under challenging underfoot conditions. Continuous dynamic integration of multimodal sensory inputs and supra-spinal commands are required for anticipatory gait modifications during challenging walking (Friston For this purpose, novel methods are required.Aspects of sensorimotor integration during challenging walking can be assessed non-invasively through the use of coherence analysis by measuring either EMG coupling or the coupling between regional EEG and EMG signals (Boonstra et al. Intramuscular coherence in the high-frequency bands, such as beta-(15–32 Hz) and gamma-band (35–60 Hz), strongly associates with oscillatory neural activity related to supra-spinal drive to the spinal cord during voluntary movements. This was previously demonstrated in cortico-muscular coherence studies in the upper (Conway et al. Intramuscular coherence in the alpha-band (8–12 Hz) may not only be modulated by EMG envelope and gait rhythm features (Halliday et al. Several studies have demonstrated that intramuscular coherence was increased during a target walking task compared to normal walking (Jensen et al. We have shown previously that, when compared to normal walking, a challenging visually guided walking task is associated with enhanced high-frequency coherence (21–44 Hz) in controls, but not in patients with severe iSCI (Zipser-Mohammadzada et al. To investigate speed-related changes during gait further, this study aimed to examine the speed-dependent modulation of intramuscular coherence during TW compared to normal walking (NW) and the robustness of the TW effect (as a modulatory intervention) in a healthy subject cohort. Furthermore, to investigate the clinical utility of intramuscular coherence as a surrogate marker for supra-spinal input, the reproducibility over time was assessed with test–retest reliability and agreement measures. Both help assessing intersession variability. Reliability measures provide information on how well coherence modulation would be reproduced, and agreement presents how close the coherence estimates are for repeated measures taking measurement errors into account (Hernaez 