Abstract
Since intramuscular hemodynamic disturbance is reported to contribute to the pathophisiology of chronic muscle pain, the efficacy of improving hemodynamic by linear polarized infra-red ray irradiation was evaluated in asymptomatic volunteers. Ten subjects were recruited from the staff and students of Okayama University. Male subjects (mean age: 25.6±1.8) who were healthy and free from chronic muscle pain participated in this study. The intramuscular hemodynamics were evaluated by using a laser tissue blood oxygen monitor (OMEGAMONITOR BOM-L1 TRW). This instrument can determine the tissue levels of oxygenated hemoglobin (Oxy Hb), deoxygenated hemoglobin (Deoxy Hb), total hemoglobin (Total Hb), and tissue blood oxygen saturation (StO2). The sensor of the instrument was placed on the skin over the right masseter muscle in each subject. Three-minute-baseline recording of each parameter was made before the linear polarized infra-red ray irradiation with the sensor in position. Then the linear polarized infra-red rays were irradiated over the right masseter for 10 min (power 80%, with 4-sec pulses delivered at 1-sec intervals), followed by continuous recording for 3 min. Before the above experimental recording, each parameter was continuously recorded under mock irradiation condition in the same manner. As a result, the median of each parameter at the baseline was not different between the irradiation and mock irradiation conditions. However, after irradiation, the median of Oxy Hb and StO2 under the irradiation condition were significantly higher compared to those under the mock irradiation condition. These results suggest that linear polarized infra-red ray irradiation over the masseter muscle increases intramuscular arterial blood and oxygen saturation levels in asymptomatic subjects.
