Fig. 2

A rat model of DOMS. a: Method applying lengthening contractions mainly to the extensor digitorum longus (EDL) muscle. One pair of insulated needle electrodes, except for their tips, was inserted near the common peroneal and sciatic nerves. While the muscle was contracted by electrical stimulation (50 Hz for 1 s), it was stretched. This was repeated 500 times with a 3 s resting period. b: Change in withdrawal threshold after lengthening contraction (LC). The withdrawal threshold decreased for three days after LC. c: c-Fos expression in the superficial dorsal horn. A significant increase in the number of c-Fos-positive neurons was observed only when the muscle was compressed after LC at L4, where the nerve innervating the EDL terminated. d: Time course of discharges of muscle thin-fibers in response to ramp mechanical stimulation (0–196 mN in 10 s, lower-most trace). The discharge rate was significantly higher in the fibers recorded from rats two days after LC (orange triangles) than in those recorded from control animals (blue circles). a and c: Modified from Taguchi et al. [78]; b: Modified from Taguchi et al. [147]; d: Modified from Taguchi et al. [83]