In a study to the possible role of overuse of the jaw muscles in the pathogenesis of jaw muscle pain, we used a protocol involving concentric and eccentric muscle contractions to provoke a state of delayed-onset muscle soreness (DOMS) in the jaw muscles of healthy individuals. We tested whether the accompanying signs and symptoms would yield the temporary diagnosis of myofascial pain according to the research diagnostic criteria for temporomandibular disorders (RDC/TMD) in these individuals.
Forty persons (mean age±SD=27.7±7.5 y) performed six, 5-minute bouts of eccentric and concentric jaw muscle contractions. Before and immediately after the exercise, and 24 hours, 48 hours, and 1 week later, self-reported muscle fatigue and pain, pain-free maximum mouth opening, pressure-pain thresholds, and the number of painful jaw muscle palpation sites were recorded.
Significant signs and symptoms of DOMS in the jaw muscles were found, which all had resolved after 1 week. In 31 (77.5%) of the participants, these signs and symptoms also gave rise to a temporary diagnosis of myofascial pain according to the RDC/TMD.
The results of this study demonstrate that an experimental protocol involving concentric and eccentric muscle contractions can provoke DOMS in the jaw muscles and the temporary diagnosis of myofascial pain according to the RDC/TMD. The results observed strengthen the supposition that the myofascial pain in TMD patients may be a manifestation of DOMS in the jaw muscles.