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. 2016 Oct;95(10):746-57.
doi: 10.1097/PHM.0000000000000490.

Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study With a Pair of Identical Twins

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Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study With a Pair of Identical Twins

Cleber Ferraresi et al. Am J Phys Med Rehabil. .
Free PMC article

Abstract

Objective: The aim of this study was to verify how a pair of monozygotic twins would respond to light-emitting diode therapy (LEDT) or placebo combined with a strength-training program during 12 weeks.

Design: This case-control study enrolled a pair of male monozygotic twins, allocated randomly to LEDT or placebo therapies. Light-emitting diode therapy or placebo was applied from a flexible light-emitting diode array (λ = 850 nm, total energy = 75 J, t = 15 seconds) to both quadriceps femoris muscles of each twin immediately after each strength training session (3 times/wk for 12 weeks) consisting of leg press and leg extension exercises with load of 80% and 50% of the 1-repetition maximum test, respectively. Muscle biopsies, magnetic resonance imaging, maximal load, and fatigue resistance tests were conducted before and after the training program to assess gene expression, muscle hypertrophy and performance, respectively. Creatine kinase levels in blood and visual analog scale assessed muscle damage and delayed-onset muscle soreness, respectively, during the training program.

Results: Compared with placebo, LEDT increased the maximal load in exercise and reduced fatigue, creatine kinase, and visual analog scale. Gene expression analyses showed decreases in markers of inflammation (interleukin 1β) and muscle atrophy (myostatin) with LEDT. Protein synthesis (mammalian target of rapamycin) and oxidative stress defense (SOD2 [mitochondrial superoxide dismutase]) were up-regulated with LEDT, together with increases in thigh muscle hypertrophy.

Conclusions: Light-emitting diode therapy can be useful to reduce muscle damage, pain, and atrophy, as well as to increase muscle mass, recovery, and athletic performance in rehabilitation programs and sports medicine.

Figures

FIGURE 1
FIGURE 1
Flowchart of the study.
FIGURE 2
FIGURE 2
A, Exercise in leg press. B, Exercise in leg extension fitness machine.
FIGURE 3
FIGURE 3
A, Array of LEDs used to LEDT. B, Light-emitting diode therapy or placebo applied immediately on quadriceps femoris muscles after each training session.
FIGURE 4
FIGURE 4
Genomic analysis of the 16 loci with short tandem repeats (STRs): amelogenin, D3S1358, D5S818, vWA, TH01, D13S317, D8S1179, D21S11, D7S820, TPOX, D16S539, D18S51, CSF1PO, FGA, penta E, penta D. Note that for both twins (twins 1 and 2) all loci have the same position and peaks, attesting their condition of identical twins (monozygotic).
FIGURE 5
FIGURE 5
Muscle performance assessing muscle fatigue resistance; 1RM test in leg press (LP) and in leg extension fitness machine (LE). Values are given in percentage (%).
FIGURE 6
FIGURE 6
Muscle damage assessed by CK at the 1st, 13th, 25th, and 36th training sessions. Values are given in percentage (%).
FIGURE 7
FIGURE 7
Delayed-onset muscle soreness assessed by VAS at the 1st, 13th, 25th, and 36th training sessions. Values are given in centimeters.
FIGURE 8
FIGURE 8
Magnetic resonance imaging of thigh muscles before (baseline) and after (final) the training program. Twelve slices and gaps were used to calculate muscle volume. Images from level 5 (slice 5) for both twins are representing the whole difference between therapies, taking into account all 12 slices and gaps. Results are presented in percentage.
FIGURE 9
FIGURE 9
Supposed effect of phototherapy by LEDT and low-level laser therapy (LLLT) in human skeletal muscle cell signaling. Colored genes were modulated with LEDT. ETC indicates mitochondrial electron transport chain.

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