ALS Amyotrophic lateral sclerosis CoV Coefficient of variation EDL Extensor digitorum longus EPI Echo planar imaging HV Healthy volunteer IRI Inter-response interval ISI Interstimulus interval MRI Magnetic resonance imaging MU Motor unit MUMRI Motor unit magnetic resonance imaging PGSE Pulsed gradient spin-echo PL Peroneus longus ROI Region of interest TA Tibialis anterior TR Repetition time 1 Introduction The ability to synchronize voluntary movements with external rhythmic cues, referred to...