Centre for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Fredrik Bajers Vej 7 D-3, Aalborg, Denmark.
PURPOSE: The aim of this human study was to apply novel topographical mapping techniques to investigate sensory and EMG manifestations of delayed-onset muscle soreness (DOMS) in multiple locations of the quadriceps. METHODS: Bipolar surface EMG signals were recorded from 11 healthy men with 15 pairs of electrodes located at 10, 20, 30, 40, and 50% of the distance from the medial, superior, and lateral border of the patella to the anterior superior iliac spine. Subjects performed sustained isometric knee extensions at 40% of the maximal force (MVC) until task failure before, 24 h, and 48 h after eccentric exercise. Pressure-pain thresholds (PPT) were assessed at the 15 locations where the EMG was recorded. RESULTS: Time to task failure was reduced after the eccentric exercise (mean +/- SD, 56.6 +/- 23 s before the eccentric exercise; 34.3 +/- 18.9 s at 24 h after exercise; and 34.3 +/- 14.4 s at 48 h after exercise). During the postexercise sustained contractions, EMG average rectified value (ARV) significantly decreased over time (P