Effects of microwave diathermy on signs and symptoms of delayed onset muscle soreness: a systematic review of Japanese primary studies

Background: Delayed onset muscle soreness (DOMS) is a common problem experienced after exercise. The use of heat has been proposed to relieve symptoms. Microwave diathermy (MWD) is a physical modality that produces deep heat in the tissues. Although its use in the Western world has become less common since the 1980s, it is still frequently used in Japan.

Objective: The purpose of this systematic review was to collect and assess Japanese language experimental research regarding the effect of MWD on signs and symptoms of DOMS.

Methods: Three Japanese databases (CiNii, Ichushi and Medical*Online) and five English databases (CINAHL, Embase, MEDLINE, Scopus and Web of Science) were searched until 2 March 2015. Only Japanese-language experimental studies were included. Two Japanese native speakers independently assessed the methodological quality of included studies using the McMaster Critical Review Form. Data were synthesised qualitatively.

Results: Three non-randomised experimental trials investigating the effects of MWD at 2450 MHz on DOMS in elbow flexors were included. All studies had moderate methodological qualities. Two studies reported significant positive effects on active range of motion (ROM) after eccentric exercises. No significant effect was identified in pain, circumference, maximal isometric strength and biochemical markers.

Conclusion: Our systematic review found limited formal evidence about the effect of MWD to improve active elbow ROM for subjects with DOMS. Real effects were difficult to assess due to the potential lack of statistical precision in data derived from small sample sizes. Future research should address the methodological flaws identified in this review, to provide more conclusive evidence.