2019 Volume 56 Issue 3 Pages 119-122
To understand the myofascial pain mechanism, we analyzed the mechanism of delayed onset muscle soreness (DOMS), which is induced by lengthening contraction and used for the study of myofascial pain syndrome. Micro injuries and following inflammation were not essential for generation of DOMS. Two pathways leading to muscular mechanical hyperalgesia were identified: One is bradykinin-like substance released during lengthening contraction-B2 bradykinin receptor-nerve growth factor pathway, the other is COX-2-prostaglandin-glial cell-line derived neurotrophic factor pathway. Both trophic factors were produced by muscle cells/satellite cells and sensitize thin-fiber muscle afferents to mechanical stimulation, resulting in muscular mechanical hyperalgesia. These results show that there are factors in the work performed by muscle in daily life that stimulate production of sensitizing neurotrophic factors, resulting in muscle mechanical hyperalgesia.
