LED Therapy: 30% Increase in Max. # of Reps in New Study, Increased Stamina and More Recent LLLT / LEDT Data

The scientists used an LEDT device from Thor on two points on the distal portion of the vastus lateralis, two points on the distal portion of the vastus medialis and two centered points along the rectus femoris (see Figure 1, right).

It may be partly my fault that most of you ask me for supplements to take to increase their performance and do not expect often not even consider the possibility of being told about technological items like a low-level laser diode device to up their gains or boost their fat loss...

When I started this blog a few years ago, I was guilty of believing that supplements would be the most relevant ergogenics for anyone who trains, myself. Today, ~2,300 articles later, this has changed: don't get me wrong - supplements can be useful, but diet, training and - at least in a few cases - even things like using light emitting diode therapy (LEDT) or low-level laser therapy (LLLT), as it is also called, are much higher on the "things that really work"-list.

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In that, it is important to point out that a recent study from the Georgia Southern University (Hemmings. 2016) is neither the first study to show significant performance / recovery benefits from LEDT, nor is it the first study I wrote about (read previous articles). The experiment Hemmings et al. conducted is yet the first to evaluate the effects of different dosages of LEDT (30 vs. 60 vs. 120 seconds on each irradiation point, see Figure 1, right) that was applied by the means of a low-level laser (THOR, London, UK) on muscular fatigue of the quadriceps after two sets of three maximal voluntary isometric contractions (MVIC).

Figure 1: Comparison of repetitions and blood lactate concentrations between all four trials; illustration of the irradiation points that were used for LEDT (Hemmings. 2016)

A total of 34 recreationally resistance trained athletes between the ages of 18 and 26 participated in four trials. Each trial included pre/post exercise blood lactate measurements, the previously hinted at MVIC and a single set of eccentric leg extensions (at 120% of the previously determined MVC) to exhaustion that was done three minutes after the initial exercises and used as a yard-stick for the recovery benefits of using 30s, 60s and 120s of LEDT compared to a 45s placebo treatment of which the subjects thought that it was yet another irradiation time that was to be tested.

LLLT therapy has also been shown to almost double the muscle gains in a study with an 8-week eccentric training program | more

LLLT and LEDT - What does the science say?: Here's how the authors explain the difference, between different forms of laser light therapy (LLT) and light emitting diode therapy (LEDT): "The difference between LLT and LEDT is the power output and depth of penetration due to various patterns in wavelengths" (Hemmings. 2016). The potential mechanism, on the other hand is always the same: "[r]esearch suggests that LLLT can prolong the binding of nitric oxide to the cytochrome C oxidase enzyme, which permits the muscle to produce more ATP in the preferred oxidative pathway" (Hemmings. 2016).

A recent meta-analysis (Nampo. 2016) evaluated both, the effects of LLLT and LEDT, on exercise capacity and muscle performance of people undergoing exercise when compared to placebo treatment. Sixteen studies involving 297 participants were included in the meta-analysis that shows a mean improvement of the number of repetitions of 3.51 reps (0.65–6.37; P = 0.02), a 4,01 second delay in time to exhaustion (2.10–5.91; P < 0.0001), and - unlike the study at hand - a sign. reduction in lactate levels (MD = 0.34 mmol/L [0.19–0.48]; P < 0.00001) and increased peak torque (MD = 21.51 Nm [10.01–33.01]; P < 0.00001).

Exercise capacity - Number of reps (left), time to exhaustion (right | Nampo. 2016)

Reason enough for the authors to conclude that their "results suggest that LASERtherapy is effective in improving skeletal muscle exercise capacity" - one thing Nampo et al. rightly add is that "the quality of the current evidence is limited" (Nampo. 2016).

As you would expect it for any effective ergogenic, the scientists observed a "significant increase in the number of repetitions performed between the placebo treatment" (Hemmings. 2016). In that, it is interesting to see that both treatments, i.e. 60 seconds (p= 0.023), as well as the 120 seconds (p=0.004) LEDT treatment triggered a significant increase in the number of reps the subjects completed - without, however, significantly affecting the accumulation of blood lactate levels in the subjects' blood. Another thing the data in Figure 1 tells us that must not be forgotten is the lack of effect of applying LEDT for only 30 seconds per irradiation point (see Figure 1, right).

Lactate is not the enemy - remember? Caffeine and Bicarbonate (NaHCO3), two proven ergogenics increase, not decrease blood lactate accumulation while still boosting subjects' performance during a standardized yo-yo performance test | learn more.

While the last-mentioned lack of effect of a shorter treatment is probably something you'd expect, the lack of effect on the accumulation of lactate may come as a surprise. Eventually, however, the exercise duration was probably simply too short to accumulate exuberant lactate levels. It is imho also questionable why the scientists used lactate, not CK or another potential measure of muscle damage (or a biopsy) to judge the effects of the LEDT treatment on a molecular level. After all, the often-heard hypothesis that the accumulation of lactate would be the reason you fail due to muscular exhaustion is - in view of the existing evidence - at least questionable.

What about gains and does timing matter? No, you don't have to be afraid that LLLT would have the same negative effects on your gains as ice-baths. It has, after all, already been shown to double the gains in a 2015 8-week study in healthy volunteers | read more! And the timing, yeah... Well, yes timing does matter! You have to apply it before the workout to see effects... at least for immediate 1RM strength gains this is the case according to a very recent study by Vanin (2016) - future studies will tell if using it post, as a recovery tool can be effective in the long-term.

As a SuppVersity reader you will, for example, remember that proven ergogenics such as bicarbonate and beta alanine increase the accumulation of lactate significantly... ok, you may argue that they simply protect the muscle from the tiring effects of lactate, but eventually there are other more likely candidates to explain the onset of fatigue such as the accumulation of other muscle metabolite, a decrease in free energy of adenosine triphosphate, limited O2 or other substrate availability, increased glycolysis, pH disturbance, increased muscle temperature, reactive oxygen species production, and altered motor unit recruitment patterns (Grassi. 2015; Poole. 2015), which could eventually explain why our muscles fatigue and why the lactate levels increase (reduced ATP, for example, will necessarily increase glycolysis and eventually the lactate accumulation).

This is only one of of several LLLT studies I've discussed in detail in older SV articles. Examples? What about this one from Aug 2015: Phototherapy Doubles Fat Loss (11 vs. 6%) & Improvements in Insulin Sensitivity (40 vs. 22%) and Helps Conserve Lean Mass in Recent 20 Weeks 'Exercise for Weight Loss Trial' | read more

Bottom line: Yeah, the scienists are right to conclude that "light emitting diode therapy had a positive effect on performance when irradiating six points on the superficial quadriceps for 60 seconds and 120 seconds prior to an eccentric leg extension" (Hemmings. 2016).

What can be refuted based on their results, however, is that this effect was a consequence of reduced lactate levels. That's in contrast to another recent study in a particularly vurnerable subgroup of hobby athletes, i.e. the hospitalized patients with heart failure in a pilot study by Bublitz et al. who found a significant decrease in lactate accumulation, albeit in response to a 6-minute walking exercise, during which LLDT was able to reduce the subjective fatigue and the previously discussed lactate concentrations, but not the subjects' performance.

Overall, it seems reasonable to conclude that further research is necessary to (a) elucidate the underlying mechanism behind the (pro-)recovery / performance enhancing effects, as well as LEDT's / LLLT's previously reported beneficial effects on insulin sensitivity and body composition and the most promising areas of application (according to the study at hand this could be resistance training / any sport that requires maximal anaerobic performance) | Comment!

References:

• Bublitz, Caroline, et al. "Acute effects of low-level laser therapy irradiation on blood lactate and muscle fatigue perception in hospitalized patients with heart failure—a pilot study." Lasers in medical science (2016): 1-7.
• Byrne, Christopher, Craig Twist, and Roger Eston. "Neuromuscular function after exercise-induced muscle damage." Sports medicine 34.1 (2004): 49-69.
• Grassi, Bruno, Harry B. Rossiter, and Jerzy A. Zoladz. "Skeletal muscle fatigue and decreased efficiency: two sides of the same coin?." Exercise and sport sciences reviews 43.2 (2015): 75-83.
• Hemmings, Thomas J. "Identifying Dosage Effect of LEDT on Muscular Fatigue in Quadriceps." Journal of Strength and Conditioning Research (2016): Publish Ahead of PrintDOI: 10.1519/JSC.0000000000001523..
• Poole, David C., and Thomas J. Barstow. "The critical power framework provides novel insights into fatigue mechanisms." Exercise and sport sciences reviews 43.2 (2015): 65-66.
• Vanin, Adriane Aver, et al. "What is the best moment to apply phototherapy when associated to a strength training program? A randomized, double-blinded, placebo-controlled trial." Lasers in Medical Science (2016): 1-10.