Does Phototherapy Enhance Skeletal Muscle Contractile Function and Postexercise Recovery? A Systematic Review

Abstract

Context Recently, researchers have shown that phototherapy administered to skeletal muscle immediately before resistance exercise can enhance contractile function, prevent exercise-induced cell damage, and improve postexercise recovery of strength and function. Objective To critically evaluate original research addressing the ability of phototherapeutic devices, such as lasers and light-emitting diodes (LEDs), to enhance skeletal muscle contractile function, reduce exercise-induced muscle fatigue, and facilitate postexercise recovery. Data Sources We searched the electronic databases PubMed, SPORTDiscus, Web of Science, Scopus, and Rehabilitation & Physical Medicine without date limitations for the following key words: laser therapy, phototherapy, fatigue, exercise, circulation, microcirculation, and photobiomodulation. Study Selection Eligible studies had to be original research published in English as full papers, involve human participants, and receive a minimum score of 7 out of 10 on the Physiotherapy Evidence Database (PEDro) scale. Data Extraction Data of interest included elapsed time to fatigue, total number of repetitions to fatigue, total work performed, maximal voluntary isometric contraction (strength), electromyographic activity, and postexercise biomarker levels. We recorded the PEDro scores, beam characteristics, and treatment variables and calculated the therapeutic outcomes and effect sizes for the data sets. Data Synthesis In total, 12 randomized controlled trials met the inclusion criteria. However, we excluded data from 2 studies, leaving 32 data sets from 10 studies. Twenty-four of the 32 data sets contained differences between active phototherapy and sham (placebo-control) treatment conditions for the various outcome measures. Exposing skeletal muscle to single-diode and multidiode laser or multidiode LED therapy was shown to positively affect physical performance by delaying the onset of fatigue, reducing the fatigue response, improving postexercise recovery, and protecting cells from exercise-induced damage. Conclusions Phototherapy administered before resistance exercise consistently has been found to provide ergogenic and prophylactic benefits to skeletal muscle.

Time response of increases in ATP and muscle resistance to fatigue after low-level laser (light) therapy (LLLT) in mice

“…However, several drugs have been prohibited from being used for this purpose as they are considered "doping" [19]. With this perspective in mind, over the last decade, some researchers have used light therapy to promote muscular pre-conditioning and to increase performance in intense exercise [15][16][17]. These reports have found good effects with this regimen of light therapy in muscular pre-conditioning, preventing muscle damage, and increasing the number of repetitions in fatigue tests.…”

“…Increased Cox activity resulting in more ATP synthesis has been the principle explanation in studies that have used LLLT to increase muscle performance before (muscular pre-conditioning) or after (muscle recovery) different types of exercise [15][16][17]. Combined with other metabolic products as lactate and accumulation of adenosine diphosphate (ADP), ATP synthesis is important for optimum muscle performance since reduced levels of ATP in muscles have been held responsible for lowered resistance of muscles to fatigue and decreased performance in many types of exercise [18].…”

Efficacy of Pulsed Electromagnetic Field on Pain and Function in Chronic Mechanical Neck Pain: A Randomized Controlled Trial

“…Researchers used many forms of small magnet or large magnetic equipment with a major claim given by researchers to the effect of these magnetic products to be considered as pain relieving modality [20,21,19] as in low back pain [28], heel pain [29] and muscle pain [30]. On the other hand, researchers used the transcranial magnetic stimulation for the treatment of depression [31] or use the small magnet to stimulate the trigger point [32].…”

Light-emitting diode therapy (LEDT) before matches prevents increase in creatine kinase with a light dose response in volleyball players

“…These studies have evaluated different wavelengths and different light sources such as diode lasers and light-emitting diodes (LEDs) [29]. Three recent studies [10,11,30] reported fascinating results and point to the effectiveness of muscular pre-conditioning using diode lasers and LEDs to prevent muscle fatigue and muscle damage (CK) when applied before (5 min) a bout of exercise.…”

“…Having in mind all previous results for muscular preconditioning [10,11,30], the present study aimed to investigate the effectiveness of the LLLT by LED therapy (LEDT) in the prevention of muscle damage (CK) in professional volleyball players during a national championship. This randomized double-blind placebo-controlled study used an array of LEDs to irradiate equally all target muscle groups [13] with different doses of light in order to establish also a therapeutic window or dose response [31] for LEDT, thus translating these studies to clinical practice.…”