Molecular effects of low-level laser therapy (808 nm) on human muscle performance

Abstract

s / Physical Therapy in Sport 13 (2012) e1–e6 e5 (p< 0.05), cyclists1⁄4 0.98 0.11 g/cm2 vs CG1⁄4 1.06 0.14 g/cm2), forearm (runners1⁄4 0.75 0.05 g/cm2 (p< 0.05), cyclists1⁄4 0.78 0.05 g/cm2 vs CG1⁄4 0.78 0.03 g/cm2) and subtotal BMD (runners1⁄4 1.27 0.13 g/cm2 (p< 0.05), cyclists1⁄4 1.16 0.05 g/cm2 vs CG1⁄4 1.17 0.08 g/cm2). Regarding MM, there was a reduction of fat mass expressed as (%) and (g) in the left arm and leg, and trunk and a subtotal reduction (p< 0.05) in both cyclists and runners compared to CG. Runners showed an increase in leanmass in the subtotal (p<0.05), while in cyclists there was a reduction of leanmass in the left arm and an increase in the left leg. Conclusions: The practice of sports leads to an increase in MM only in the segments where vigorous contractions are found. In contrast, BMD may not suffer great changes, with its values often being lower than those found in CG, thus may expose athletes to fractures. doi:10.1016/j.ptsp.2012.03.009 MOLECULAR EFFECTS OF LOW-LEVEL LASER THERAPY (808 NM) ON HUMAN MUSCLE PERFORMANCE Cleber Ferraresi , Rodrigo Panepucci , Rodrigo Reiff , Euclides Junior , Vanderlei Bagnato , Nivaldo Parizotto a a Federal University of Sao Carlos, Brazil Hemotherapy Center of Ribeirao Preto, Brazil University of Sao Paulo, Brazil Purpose: Low-level laser therapy (LLLT) has been applied to repair and increase humanmuscle performance. However, there are no studies on the effects of LLLT on molecular mechanisms that control the functions of muscle cells. The purpose of this study was to investigate whether strength training with LLLT can modulate gene expressions of the whole human genome to accelerate repair and increase human muscle performance during physical strength training. Methods: Ethics Committee in Human Research of Federal University of Sao Carlos (n 040/2011) approved this clinical trial study. The study included 10 healthy men, randomly allocated into two equal groups: training with LLLT (TLG group) and training alone (TG group). All subjects underwent biopsy of the vastus lateralis muscle before and after the training program for analysis of differential gene expression using microarrays. The training program had an intensity of 80% of one-repetition maximum leg press 45 (1RMleg) and a volume of 05 sets of 10 repetitions, twice a week for 12 weeks. Infrared LLLT (808 nm) was applied to the quadriceps muscles of both legs for the TLG subjects after each workout, totaling 50 J per session. The groups were compared by repeated measures ANOVA (2 2) and percentage changes in performance and gene expression using the Mann-Whitney test. Results: An increase of 65% in 1RMleg of the TLG group compared to 26% increase in the TG group (p1⁄4 0.007). TLG was the only group to super express significantly the genes PPARGC1-a (65%, p1⁄4 0.005),mTOR (31%, p1⁄4 0.003), VEGF (31%, p< 0.001) and sub express the genesMuRF1 (-32%, p1⁄4 0.016) and IL-1b (-66%, p< 0.001) in preliminary analyses of gene expression. Conclusions: Physical strength training with LLLT can modulate some important functions of human muscle cells, such as increase the gene expression of mitochondrial biogenesis (PPARGC1-a), protein synthesis (mTOR) and tissue angiogenesis (VEGF). Furthermore, physical strength training with LLLT decreases gene expression of protein degradation (MuRF1) and inflammation (IL-1b), suggesting improved muscle repair for a better muscle performance in physical strength training.