Association of photobiomodulation therapy and therapeutic exercises in relation to pain intensity and neck disability in individuals with chronic neck pain: a systematic review of randomized trials.

Exercise is often pointed out as an effective form of treatment in the clinical management of chronic neck pain (CNP). However, due to its complex range of causal factors and great diversity of signs and symptoms, other resources such as photobiomodulation therapy (PBMT) have been routinely used for the treatment of CNP. The aim of this study was to systematically review the literature on the use of the association of PBMT and therapeutic exercises in relation to pain intensity and neck disability in individuals with CNP. PubMed, Medline (via Ovid), Embase (via Ovid), Cinahl (via Ebsco), and Central (via Cochrane library) databases were searched using the following terms: "laser," "low-level laser," "photobiomodulation," "light emitting diodes," "phototherapy," "exercise," "chronic neck pain." After verification and implementation of eligibility criteria, seven manuscripts were considered eligible for data analysis. These manuscripts had methodological quality between 5 and 8 points on the PEDro scale. Most studies used low infrared laser therapy to perform PBMT, with a wide range of parameters and energy density between 2 and 7 J/cm2 and a total treatment time between 2 and 6 weeks. Four studies showed significant benefits in terms of pain intensity at short-term follow-up and one at intermediate-term follow-up. However, only one showed a minimal clinically important change. No studies have shown significant improvement in disability. This review demonstrates that the association of PBMT with therapeutic exercises in general promotes significant benefits only for the intensity of pain. However, it does not seem to promote a minimally effective clinical difference in individuals with CNP.