Changes in muscle temperature induced by 434 MHz microwave hyperthermia

• Published in: British journal of sports medicine 2007-07, Vol.41 (7), p.425-429
• Main Authors: Ichinoseki-Sekine, Noriko, Naito, Hisashi, Saga, Norio, Ogura, Yuji, Shiraishi, Minoru, Giombini, Arrigo, Giovannini, Valentina, Katamoto, Shizuo
• Format: Article
• Language: English
• Subjects: Adult; Athletic Injuries - therapy; Body Temperature; CK, creatine kinase; creatine kinase; Fever; Heat; heat shock protein; HSP; HSP, heat shock protein; Humans; Hyperthermia, Induced - adverse effects; Hyperthermia, Induced - methods; Male; Microwaves - adverse effects; Microwaves - therapeutic use; Muscle, Skeletal - injuries; Muscular Diseases - therapy; Muscular system; Musculoskeletal system; Original; Original articles; Skin; Sports medicine; Studies; Temperature; Treatment Outcome; Ultrasonic imaging; Water temperature
• ISSN: 0306-3674; 1473-0480
• DOI: 10.1136/bjsm.2006.032540

Objective: To investigate the changes in temperature of human muscle during microwave hyperthermia. Methods: Skin surface and muscle temperatures were measured in 11 healthy adult men (mean (SD) age 24.3 (2.2) years; height 174.2 (6.1) cm; weight 70.0 (5.3) kg) during a 30 min exposure of the thigh to 434 MHz microwave hyperthermia. Skin temperature was maintained at the pilot temperature of 40°C, and the temperature of the water in the bolus was 38°C. The peak power output was set at 60 W and controlled automatically to maintain the pilot temperature. The temperature was measured in the vastus lateralis muscle at an average muscle depth of 2.0 (0.2) cm, using a 23 G Teflon-shielded thermocouple. Biopsy specimens were obtained for light microscopy from three subjects. A muscle-equivalent phantom was used to evaluate the vertical heating pattern. Results: Both skin and muscle temperatures increased from baseline, and muscle temperature was higher than skin temperature (skin temperature 39.2 (0.5)°C, temperature rise 5.0 (1.5)°C; muscle temperature 43.7 (0.8)°C, temperature rise 8.9 (1.4)°C). At the end of the hyperthermia treatment, muscle temperature decreased to 39.8 (0.9)°C, but was still 4.8 (1.5)°C higher than the baseline. No signs of muscle damage were observed on the basis of the blood creatine kinase activity and histological sections. Conclusions: The results show that the 434 MHz microwave hyperthermia treatment increased and maintained muscle temperature locally by 6.3–11.4°C without muscle damage. These findings suggest that the microwave hyperthermia system provides effective and safe treatment.