Effect of low-level laser therapy on muscle adaptation to knee extensor eccentric training
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Eccentric training has been popularized for physical conditioning and prevention/rehabilitation of musculoskeletal disorders, especially due to the expressive responses in terms of muscular strength gain. In view of evidence that low-level laser therapy (LLLT) is able to increase exercise performance and accelerate post-exercise recovery, the aim of this study was to verify the effect of LLLT on hypertrophy and strengthening of knee extensor muscles submitted to eccentric training.
Thirty healthy male subjects were randomized into three groups: Control Group (CG), Training Group (TG) and Training + LLLT Group (TLG). CG received no intervention, while TG and TLG were engaged on an 8-week knee extensor isokinetic eccentric training program. Only subjects from TLG were treated with LLLT (wavelength = 810 nm; power output = 200 mW; total dosage = 240 J) before each training session. Knee extensor muscle thickness and peak torque were assessed through ultrasonography and isokinetic dynamometry, respectively.
CG presented no changes in any variable throughout the study, while eccentric training led to significant increases in muscle thickness and peak torque in TG and TLG. Subjects from TLG reached significantly higher percent changes compared to subjects from TG for sum of muscles’ thicknesses (15.4 vs. 9.4 %), isometric peak torque (20.5 vs. 13.7 %), and eccentric peak torque (32.2 vs. 20.0 %).
LLLT applied before eccentric training sessions seems to improve the hypertrophic response and muscular strength gain in healthy subjects.
KeywordsPhototherapy Resistance training Eccentric exercise Quadriceps femoris
Analysis of variance
Light-emitting diode therapy
Low-level laser therapy
Rectus femoris muscle thickness
Vastus lateralis muscle thickness
Vastus medialis muscle thickness
Concentric peak torque
Eccentric peak torque
Isometric peak torque
Training + LLLT group
Sum of muscles’ thicknesses
The authors would like to thank Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Brazil) and Fundação de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS, Brazil) for financial support.
- de Almeida P, Lopes-Martins RA, Tomazoni SS, Silva JA Jr, de Carvalho Pde T, Bjordal JM, Leal Junior EC (2011) Low-level laser therapy improves skeletal muscle performance, decreases skeletal muscle damage and modulates mRNA expression of COX-1 and COX-2 in a dose-dependent manner. Photochem Photobiol 87:1159–1163CrossRefPubMedGoogle Scholar
- Gerber JP, Marcus RL, Dibble LE, Greis PE, Burks RT, LaStayo PC (2009) Effects of early progressive eccentric exercise on muscle size and function after anterior cruciate ligament reconstruction: a 1-year follow-up study of a randomized clinical trial. Phys Ther 89(1):51–59. doi: 10.2522/ptj.20070189 CrossRefPubMedGoogle Scholar
- Leal-Junior EC, Vanin AA, Miranda EF, de Carvalho PD, Dal Corso S, Bjordal JM (2013) 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 [Epub ahead of print]Google Scholar
- Paolillo FR, Corazza AV, Borghi-Silva A, Parizotto NA, Kurachi C, Bagnato VS (2013) Infrared LED irradiation applied during high-intensity treadmill training improves maximal exercise tolerance in postmenopausal women: a 6-month longitudinal study. Lasers Med Sci 28:415–422CrossRefPubMedGoogle Scholar