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Lasers Med Sci. 2018 Apr;33(3):453-460. doi: 10.1007/s10103-017-2347-y. Epub 2017 Nov 9.

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

Author information

1
Laboratório de Pesquisa do Exercício, Escola de Educação Física, Fisioterapia e Dança, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. fabiolanferdini@gmail.com.
2
Universidade Regional Integrada do Alto Uruguai e das Missões, Santo Ângelo, RS, Brazil. fabiolanferdini@gmail.com.
3
Laboratório de Pesquisa do Exercício, Escola de Educação Física, Fisioterapia e Dança, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
4
University of Calgary, Calgary, AB, Canada.
5
Departamento de Fisioterapia, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
6
Laboratório de Biomecânica, Universidade Federal de Santa Catarina, Florianópolis, RS, Brazil.
7
Portugal Football School, Portuguese Football Federation, Oeiras, Portugal.
8
Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University Institute of Maia, ISMAI, Portugal.

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 VO2 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 (VO2MAX) and maximal power output (POMAX), 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 POMAX. 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 VO2 amplitude, VO2 delay time, time constant (tau), and O2 deficit. Tau and O2 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 VO2 amplitude and VO2 delay time. In conclusion, LLLT decreases tau and O2 deficit during time-to-exhaustion tests in competitive cyclists, and these changes in VO2 kinetics response can be one of the possible mechanisms to explain the ergogenic effect induced by LLLT.

KEYWORDS:

Cycling; Phototherapy; Sport performance; Time-to-exhaustion; VO2 kinetics

PMID:
29119418
DOI:
10.1007/s10103-017-2347-y
[Indexed for MEDLINE]

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