Low-level laser therapy improves the VO2 kinetics in competitive cyclists

Abstract

Some evidence supports that low-level laser therapy (LLLT) reduces neuromuscular fatigue, so incrementing sports performance. A previous randomized controlled trial of our group showed increased exercise tolerance in male competitive cyclists treated with three different LLLT doses (3, 6, and 9 J/diode; or 135, 270, and 405 J/thigh) before time-to-exhaustion cycling tests. Now, the present study was designed to evaluate the effects of these LLLT doses on the VO kinetics of athletes during cycling tests. Twenty male competitive cyclists (29 years) participated in a crossover, randomized, double-blind, and placebo-controlled trial. On the first day, the participants performed an incremental cycling test to exhaustion to determine maximal oxygen uptake (VO) and maximal power output (PO), as well as a familiarization with the time-to-exhaustion test. In the following days (2 to 5), all participants performed time-to-exhaustion tests at PO. Before the exhaustion test, different doses of LLLT (3, 6, and 9 J/diode; or 135, 270, and 405 J/thigh, respectively) or placebo were applied bilaterally to the quadriceps muscle. All exhaustion tests were monitored online by an open-circuit spirometry system in order to analyze the VO amplitude, VO delay time, time constant (tau), and O deficit. Tau and O deficit were decreased with LLLT applications compared to the placebo condition (p < 0.05). No differences (p > 0.05) were found between the experimental conditions for VO amplitude and VO delay time. In conclusion, LLLT decreases tau and O deficit during time-to-exhaustion tests in competitive cyclists, and these changes in VO kinetics response can be one of the possible mechanisms to explain the ergogenic effect induced by LLLT.

Effects of Endurance Running Training Associated With Photobiomodulation on 5-Km Performance and Muscle Soreness: A Randomized Placebo-Controlled Trial

“…Despite the important findings, the present study had some limitations; for example, the lack of another control group with only the PBM application and without endurance running training. Furthermore, it is important to note that because different PBM parameters (e.g., wavelength, time to apply PBM, dosage) influence the responses of different variables (Lanferdini et al, 2018b; Miranda et al, 2018), we suggest that the dosage and the time of application used could influence the magnitude of our results. For example, Ferraresi et al (2016a) in a recent review on PBM in human muscle tissue, reported some evidence in favor of applying PBM before exercise in association with training programs, as used in our study, to increase performance, limit muscle damage and prevent pain from 1 h until 72–96 h after exercise.…”

What is the optimal time-response window for the use of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) for the improvement of exercise performance and recovery, and for how long the effects last? A randomized, triple-blinded, placebo-controlled trial

“…The first clinical trial in this field showed that PBMT before an exercise session could enhance the performance of high-level volleyball athletes (number of repetitions), decrease the delayed onset muscle fatigue (time until exhaustion), and prevent the expected increase of blood lactate levels [ 6 ]. After this pioneering clinical trial [ 6 ], PBMT used alone or in combination to static magnetic fields (sMF) have shown positive results in different kinds of exercises and protocols such as repeated contractions [ 6 , 7 ], isometric contractions [ 8 ], progressive-intensity running [ 9 – 11 ], cycling [ 12 , 13 ], eccentric contractions [ 14 – 17 ], strength training [ 18 , 19 ], endurance training in treadmill [ 20 ] and even in field tests [ 21 ]. Regarding exercise recovery, both PBMT and PBMT-sMF have shown better effects than other agents classically used for this aim, such as cryotherapy for instance [ 22 – 24 ].…”

“…There is evidence that PBMT combined with sMF (PBMT-sMF) is able to promote ergogenic effects in a similar way to isolated PBMT [ 19 – 21 , 29 – 31 ]. Currently there is an increasing body of evidence for the use of both isolated PBMT and PBMT-sMF [ 32 , 33 ] with several aspects regarding the application of these therapies being elucidated, such as: optimal doses [ 12 , 13 , 15 , 16 ], optimal power output [ 17 ], and even comparisons between different devices commercially available [ 34 ]. However, the time-response window is still a matter of debate.…”

Does photobiomodulation therapy combined to static magnetic field (PBMT-sMF) promote ergogenic effects even when the exercised muscle group is not irradiated? A randomized, triple-blind, placebo-controlled trial

“…In recent years, this therapy has shown positive effects in the management of several musculoskeletal disorders and inflammatory conditions to promote pain relief and wound healing [5][6][7][8][9][10][11]. Many studies have reported that PBMT increases muscle performance, reduces fatigue, and improves muscle recovery in athletes, physically active, and sedentary individuals [12][13][14][15][16][17][18][19][20][21][22]. The main mechanism of action of PBMT include the interaction of photons with cytochrome c-oxidase, a mitochondrial photoreceptor [2], leading to greater transfer of electrons and consequently mitochondrial respiratory chain activation, which increases mitochondrial adenosine triphosphate (ATP) production [23].…”