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

• Published in: Lasers in medical science 2018-04, Vol.33 (3), p.453-460
• Main Authors: Lanferdini, Fábio J., Krüger, Renata L., Baroni, Bruno M., Lazzari, Caetano, Figueiredo, Pedro, Reischak-Oliveira, Alvaro, Vaz, Marco A.
• Format: Article
• Language: English
• Subjects: Athletes; Bicycling; Cycles; Delay; Dentistry; Exhaustion; Fatigue; Kinetics; Lasers; Level (quantity); Medicine; Medicine & Public Health; Muscles; Optical Devices; Optics; Original Article; Oxygen consumption; Oxygen uptake; Photonics; Quadriceps muscle; Quantum Optics; Randomization; Tau protein; Therapy; Thigh; Time constant
• ISSN: 0268-8921; 1435-604X
• DOI: 10.1007/s10103-017-2347-y

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 2 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 2MAX ) and maximal power output (PO MAX ), 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 MAX . 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 2 amplitude, VO 2 delay time, time constant (tau), and O 2 deficit. Tau and O 2 deficit were decreased with LLLT applications compared to the placebo condition ( p   0.05) were found between the experimental conditions for VO 2 amplitude and VO 2 delay time. In conclusion, LLLT decreases tau and O 2 deficit during time-to-exhaustion tests in competitive cyclists, and these changes in VO 2 kinetics response can be one of the possible mechanisms to explain the ergogenic effect induced by LLLT.