Low Level Laser Therapy (LLLT) Almost Doubles Muscle Gains & Ramps Up Concentric & Eccentric Peak Torque Development During 8-Week Eccentric Training Program

No, this is no photo from the study. Obviously the LLLT was applied to the legs, but LLLT is also used for shoulder and general muscle pain.

I am usually very skeptical when it comes to therapies that sound extremely cool on paper, but have hitherto only proven to improve markers of muscle damage and/or growth. Before I saw the latest paper from the Universidade Federal de Ciências da Saúde de Porto Alegre (Baroni. 2015) low level laser therapy aka LLLT fell into this exact category of promising, but not proven post-exercise recovery therapies (Baroni 2010a, b).

Said study involved thirty healthy male subjects without previous training/LLLT experience were randomized into three groups.
The subjects in the control group remained sedentary for the whole 8-week study period. The subjects who had been randomized to the training (TG) and training + LLLT (TLG) groups, on the other hand, were engaged in an 8-week knee extensor isokinetic eccentric training program.

Figure 1: Application points (black circles) used for LLLT (Baroni. 2014)

"Volunteers allocated in TG and TLG were engaged in an 8-week knee extensor eccentric training program. Training sessions were performed twice a week (except for the 1st and 5th weeks), with a minimum interval of 72 h between ses sions. Subjects performed only one training session in the 1st training week to allow for progressive introduction to the training regimen and to avoid having participants undertake an exercise session in the presence of clinical symptoms of exercise-induced muscle damage, such as delayed onset mus cle soreness (Byrne et al. 2004). At the 5th training week, only one training session was performed because the training volume was increased from three to four sets of 10 maximal eccentric contractions.

Each training session was initiated by a 5-min warm-up exercise on a cycle ergometer, followed by eccentric exercises on the isokinetic dynamometer performed according to the protocol of Baroni et al. (2010a). Before each eccentric contraction, the limb was extended passively to 30° of knee flxion and subjects were encouraged to per form a maximal contraction of the knee extensor as soon as the dynamometer arm reached this position. In response to the subject’s extensor torque, the dynamometer drove the seg ment to 90° of knee flxion (range of motion = 60°) at an angular velocity of 60° s−1. A 1-min rest period was respected between sets and verbal encouragement was provided by team throughout the training session" (Baroni. 2014).

Obviously, only the subjects from TLG were treated with LLLT (wavelength = 810 nm; power output = 200 mW; total dosage = 240 J) before each training session, too.

Figure 2: Muscle size and peak torque changes over the course of the 8-week study (Baroni. 2014).

Knee extensor muscle thickness and peak torque were assessed through ultrasonography and isokinetic dynamometry, respectively; and as the data in Figure 2 indicates. Using the low-level laser therapy using a Thor Photomedicine infra-red laser cluster probe consisting of fie GaAlAs laser diodes (810 nm) immediately before each training session with the probe held stationary in skin contact at a 90°
angle with slight pressure had significant effects on the outcome of the 8-week eccentric strength training protocol.
References:

• Avni, Dorit, et al. "Protection of skeletal muscles from ischemic injury: low-level laser therapy increases antioxidant activity." Photomedicine and Laser Therapy 23.3 (2005): 273-277.
• Baroni, Bruno Manfredini, et al. "Low level laser therapy before eccentric exercise reduces muscle damage markers in humans." European journal of applied physiology 110.4 (2010a): 789-796.
• Baroni, Bruno Manfredini, et al. "Effect of light-emitting diodes therapy (LEDT) on knee extensor muscle fatigue." Photomedicine and laser surgery 28.5 (2010b): 653-658.
• Baroni, Bruno Manfredini, et al. "Effect of low-level laser therapy on muscle adaptation to knee extensor eccentric training." European journal of applied physiology (2014): 1-9.
• Byrne C, Twist C, Eston R. Neuromuscular function after exercise-induced muscle damage: theoretical and applied implications. Sports Med 34 (2014):49–69.
• de Brito Vieira, Wouber Hérickson, et al. "Effects of low-level laser therapy (808 nm) on isokinetic muscle performance of young women submitted to endurance training: a randomized controlled clinical trial." Lasers in medical science 27.2 (2012): 497-504.
• Ferraresi, Cleber, et al. "Effects of low level laser therapy (808 nm) on physical strength training in humans." Lasers in medical science 26.3 (2011): 349-358.
• Karu, T., L. Pyatibrat, and G. Kalendo. "Irradiation with He Ne laser increases ATP level in cells cultivated in vitro." Journal of Photochemistry and photobiology B: Biology 27.3 (1995): 219-223.
• Silveira, Paulo CL, et al. "Evaluation of mitochondrial respiratory chain activity in muscle healing by low-level laser therapy." Journal of Photochemistry and Photobiology B: Biology 95.2 (2009): 89-92.