Clinical Scenario
Low-level laser therapy (LLLT) has been a controversial topic for its use in athletic recovery, mainly due to the inconsistency in research regarding the timing of application for this modality. Articles on LLLT have assessed its effectiveness in untrained humans through pain scales, functional scales, and blood draws, and it has been found capable in nonathletic rehabilitative use. The controversy lies with LLLT use in the recovering athlete, who needs to perform at peak levels on a day-to-day basis. Not only do athletes need to perform at high levels, but each sport is unique in the metabolic demands placed on the athletes’ bodies; this is where the timing of LLLT is controversial. Timing of this modality can alter chemical mediators of the inflammatory process and inhibit damaging enzymes, more specifically, blood lactate (BL) and creatine kinase (CK). During soccer contests, it is a common problem for field athletes to have an average CK level of 800 U/L and BL of 8 mmol·L, increasing delayed-onset muscle soreness (DOMS) and muscular fatigue.1,2 Micro-CK level elevation is also associated with cellular membrane damage, localized hypoxia, and disruption of electrolyte balances, causing a stunting of the recovery process.3 For these reasons, CK and BL are precipitators of muscle fatigue and function and were selected for the specified purpose of controlling these mediators that cause DOMS, fatigue, and delayed recovery responses with LLLT.
Focused Clinical Question
Does LLLT decrease muscle-damaging mediators effecting player fatigue and DOMS after performance in soccer athletes versus sham treatment?
Clinical Bottom Line
The LLLT either at 10, 30, or 50 J performed at a minimum of 2 locations on the rectus femoris, vastus lateralis, and vastus medialis bilaterally for 10 seconds each is significant in decreasing blood serum levels of BL and CK when performed postexercise.4–6
Search Strategy
Guided Search terms
- •Patient/Client group: male or female soccer athletes, collegiate soccer athletes, professional college athletes
- •Intervention: low-level laser therapy, light therapy
- •Comparison: sham, no low-level laser therapy
- •Outcome: creatine kinase, blood lactate
Databases Searched
–PubMed
–Google Scholar
–ScienceDirect
–Physiotherapy Evidence Database (PEDro)
Inclusion and Exclusion Criteria
Inclusion Criteria
- •Use of LLLT
- •Evaluation of CK or BL
- •LLLT on soccer athletes
- •Evaluation of chemical mediators after simulated or actual performance
- •PEDro score ≥5
Exclusion Criteria
- •Animal studies
- •Use of another modality in conjunction with LLLT
Search Results
After searching the included databases, 3 studies were identified with PEDro scores of ≥8 and included in this appraisal. Table 1 shows the individual breakdown of scores.
Articles Score
| Article | Study design | PEDro score |
|---|---|---|
| Dos Reis et al4 | Randomized, double-blind, placebo-controlled trial | 8/10 |
| Leal-Junior et al5 | Randomized, double-blind, placebo-controlled, crossover trial | 8/10 |
| Aver Vanin et al6 | Randomized, double-blind, placebo-controlled trial | 10/10 |
Abbreviation: PEDro, Physiotherapy Evidence Database.
Summary of Best Evidence
The LLLT was effective in decreasing serum CK and BL when applied preperformance or postperformance; however, the greatest decrease was evident when laser therapy was performed postperformance (Table 2).4–6
Study Parameters and Results
| Dos Reis et al4 | Leal-Junior et al5 | Aver Vanin et al6 | |
|---|---|---|---|
| Participants | 27 male soccer athletes | 11 male soccer athletes | 28 male soccer athletes |
| Exercise | 75% 1-RM knee extension to fatigue | 30 s maximal Wingate | Eccentric exercise protocol |
| LLLT frequency | 830 nm | 830 nm | 810 nm |
| LLLT dosage | –Placebo: 0 J per leg each session (0 J at each site) 10 s at each of 42 points on quadriceps on days 1 and 8 –Preexercise laser group: 25.2 J per leg each session (0.6 J at each site) 10 s at each of 42 points on quadriceps on days 1 and 8 –Postexercise laser group: 25.2 J per leg each session (0.6 J at each site) 10 s at each of 42 points on quadriceps on days 1 and 8 | –Placebo: 0 J per leg (0 J at each site) 30 s at each of the 5 points on bilateral rectus femoris (10 total points) –Laser group: 30 J per leg (3 J at each site) 30 s at each of the 5 points on bilateral rectus femoris (10 total points) | –Group A: 60 J of total irradiated energy (10 J in each site) with 10 s of irradiation at each site (60 s of total irradiation time) –Group B: 180 J of total irradiated energy (30 J in each site) with 30 s of irradiation at each site (180 s of total irradiation time) –Group C: 300 J of total irradiated energy (50 J in each site) with 50 s of irradiation at each site (300 s of total irradiation time) –Group D: 0 J of total irradiated energy (0 J in each site) with 20 s of sham irradiation at each site (120 s of total time), but without effective irradiation |
| Treatment area |  |  |  |
| When LLLT was performed | Preperformance or postperformance LLLT | Preperformance LLLT | Preperformance LLLT |
| CK results | –Post-LLLT: Significantly decreased CK levels (P < .01) when compared with placebo group at 10- and 15-min blood draw on both days 1 and 8 –Pre-LLLT: Significantly decreased CK levels (P < .05) when compared with placebo at 10- and 15-min intervals on day 1 and 8 | Not applicable | –Group A: 10 J LLLT dose significantly decreased (P < .05) CK serum levels compared with placebo in 24-, 48-, 72-, -and 96-h time intervals. –Group B: 30 J LLLT did not significantly decrease (P > .05) CK with LLLT at 24, 48, 72, and 96 h postexercise. –Group C: 50 J LLLT dose significantly decreased CK (P < .05) at intervals of 24, 48, 72, and 96 h after performance. |
| BL results | –Post-LLLT: Significantly decreased BL levels (P < .01) when compared with placebo at 10- and 15-min intervals when compared with placebo group on days 1 and 8 –Pre-LLLT: Decreased BL levels at 10- and 15-min intervals on day 1 and 15-min interval on day 8. Results were not clinically significant on either day. | Laser group: Pre-LLLT significantly decreased BL levels (P < .01) 15 min postexercise was completed when compared with placebo group. | Not applicable |
| Conclusion | Both pre-LLLT and post-LLLT significantly reduced BL and CK vs placebo group. The greatest differences were noted when postexercise LLLT was performed at 10- and 15-min intervals. | Preexercise LLLT performed reduced BL vs placebo after 15 min of completing the exercise program. | Preexercise LLLT reduced CK levels when evaluated postexercise. However, differences were not noted until 24 h later on 10 and 50 J. |
Abbreviations: 1-RM, 1-repetition maximum; BL, blood lactate; CK, creatine kinase; LLLT, low-level laser therapy.
Implications for Practice, Education, and Future Research
Blood lactate is a byproduct of anaerobic glycolysis and has been blamed for DOMS; however, BL is normally filtered and converted back into pyruvate within 6- to 24-hours postexercise in trained individuals.7 The enzyme responsible for this conversion is known as lactate dehydrogenase (LDH). LDH is found in liver, heart, brain, and muscle cell cytoplasm and changes the molecular structure of BL (C3H6O3) to pyruvate (C3H4O3).8 When conversion of BL takes place in muscular tissue, LDH is primed by nicotinamide adenine dinucleotide (NAD+), which is a metabolic transporter in energy production within the mitochondria.7,8 Laser therapy is able to stimulate the mitochondrial respiratory chain, which signals NAD+ to the mitochondria.9 With increased signaling of the NAD+ primer, LDH is able to convert BL into pyruvate regardless if preperformance or postperformance laser therapy is performed on athletes, specifically in the quadriceps muscles of soccer players. Dos Reis et al4 recorded a significant difference in BL when LLLT is performed postperformance when compared with placebo (P < .01). Even though BL was lower versus placebo when LLLT was performed preexercise, there was no clinically significant difference. BL levels after performance in dos Reis et al4 were placebo—4 mmol/L after 10 minutes, prelaser group—3 mmol/L after 10 minutes, and postlaser group—2 mmol/L after 10 minutes. Leal-Junior et al5 noticed BL levels decreased after 15 minutes when LLLT was performed pre-Wingate test when compared with placebo (P <.01): placebo—10.52 mmol·L and laser group—8.55 mmol·L. The greatest difference in BL levels came when LLLT was performed postexercise.
Creatine kinase is an enzyme that can be considered either good or bad to the body. CK is associated with muscle damage after strenuous exercise and has been linked to DOMS.3 CK is also used to convert adenosine diphosphate to adenosine triphosphate (ATP) using creatine phosphate.3,7,8 This conversion is the first mechanism for producing energy when the body begins exercise. When the body is at rest, a CK polymer (mitochondrial creatine kinase) is used to reconvert ATP and creatine back to adenosine diphosphate and creatine phosphate for future energy use.3 To create adenosine diphosphate and creatine phosphate for future use, there needs to be an abundance of ATP readily accessible. By performing laser therapy over the muscle group that was worked, cytochrome c and the rest of the mitochondria are stimulated to continue making ATP for energy use.10,11 By producing ATP, CK is utilized to store energy, creating molecules for future energy use. Aver Vanin et al6 noticed significant decreases (P < .05) in CK levels when laser therapy was performed at 10 and 50 J preexercise at 24-, 48-, 72-, and 96-hour time intervals. Dos Reis et al4 recorded CK levels that decreased significantly when laser therapy was performed postexercise compared with placebo within 15 minutes on day 8 (second session): placebo—400 U/L, prelaser—200 U/L, and postlaser—100 U/L. The greatest effects of laser therapy in reducing CK levels and utilizing CK were observed when postexercise LLLT was performed.
Performing either preperformance or postperformance laser therapy can decrease CK, and postexercise LLLT decreases BL. The greatest effects from laser therapy are performing postperformance therapy at 10, 30, or 50 J of total energy performed at a minimum of 2 locations on the rectus femoris, vastus lateralis, and vastus medialis bilaterally for 10 seconds each. Further research is needed to assess the reliability and validity of the use of LLLT in rehabilitation and recovery in other sports. Further research is also needed to assess BL and CK when postexercise LLLT is performed and to evaluate the differences in male versus female soccer players.
References
- 1.↑
Barbosa D, Rodrigo C, Morandi RF, et al. Creatine kinase kinetics in professional soccer players during a competitive season. Rev Bras de Cineantropometria Desempenho Humano. 2011;13(3):189–194. doi:10.5007/1980-0037.2011v13n3p189
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Bangsbo J, Iaia FM, Krustrup P. Metabolic response and fatigue in soccer. Int J Sports Physiol Perform. 2007;2(2):111–127. PubMed ID: 19124899
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Baird M, Graham G, Baker J, Bickerstaff G. Creatine-kinase- and exercise-related muscle damage implications for muscle performance and recovery. J Nutr Metab. 2012;2012:960363. PubMed ID: 22288008 doi:10.1155/2012/960363
- 4.↑
Dos Reis F, Da Silva A, Lararaia E, et al. Effects of pre- or post-exercise low-level laser therapy (830 nm) on skeletal muscle fatigue and biochemical markers of recovery in humans: double-blind placebo-controlled trial. Photomed Laser Surg. 2014;32(2):106–112. PubMed ID: 24456143 doi:10.1089/pho.2013.3617
- 5.↑
Leal-Junior E, Lopes-Martins R, Baroni B, et al. Effect of 830 nm low-level laser therapy applied before high-intensity exercises on skeletal muscle recovery in athletes. Lasers Med Sci. 2009;24:857. PubMed ID: 19057981 doi:10.1007/s10103-008-0633-4
- 6.↑
Aver Vanin A, De Marchi T, Tomazoni S, et al. Pre-exercise infrared low-level laser therapy (810 nm) in skeletal muscle performance and postexercise recovery in humans, what is the optimal dose? A randomized, double-blind, placebo-controlled clinical trial. Photomed Laser Surg. 2016;34(10):473–482. PubMed ID: 27575834 doi:10.1089/pho.2015.3992
- 8.↑
Powers S, Howley E. Exercise Physiology: Theory and Application to Fitness and Performance. 8th ed. New York, NY: McGraw Hill; 2012.
- 9.↑
Leal-Junior E, Aver Vanin A, Miranda E, de Carvalho P, Corso S, Bjordal J. Effect of phototherapy (low-level laser therapy and light-emitting diode therapy) on exercise performance and markers of exercise recovery: a systematic review with meta-analysis. Lasers Med Sci. 2015;30(2):925–939. doi:10.1007/s10103-013-1465-4
- 10.↑
De Marchi T, Schmitt VM, da Sliva Fabro CD, et al. Phototherapy for improvement of performance and exercise recovery: comparison of 3 commercially available devices. J Athl Train. 2017;52(5):429–438. PubMed ID: 28319422
