%A Dutra,Yago Medeiros
%A Claus,Gabriel Machado
%A Malta,Elvis de Souza
%A Seda,Daniela Moraes de Franco
%A Zago,Anderson Saranz
%A Campos,Eduardo Zapaterra
%A Ferraresi,Cleber
%A Zagatto,Alessandro Moura
%D 2021
%J Frontiers in Physiology
%C
%F
%G English
%K Low-level laser therapy,Exercise tests,Ergogenic effects,Regional Blood Flow,cardiorespiratory fitness
%Q
%R 10.3389/fphys.2020.607302
%W
%L
%M
%P
%7
%8 2021-January-15
%9 Original Research
%#
%! Photobiomodulation and exercise performance
%*
%<
%T Photobiomodulation 30 min or 6 h Prior to Cycling Does Not Alter Resting Blood Flow Velocity, Exercise-Induced Physiological Responses or Time to Exhaustion in Healthy Men
%U https://www.frontiersin.org/articles/10.3389/fphys.2020.607302
%V 11
%0 JOURNAL ARTICLE
%@ 1664-042X
%X PurposeThe aim of the current study was to investigate the effects of photobiomodulation therapy (PBMT) applied 30 min or 6 h prior to cycling on blood flow velocity and plasma nitrite concentrations at rest, time to exhaustion, cardiorespiratory responses, blood acid-base balance, and K+ and lactate concentrations during exercise.MethodsIn a randomized, crossover design, 13 healthy untrained men randomly completed four cycling bouts until exhaustion at the severe-intensity domain (i.e., above respiratory compensation point). Thirty minutes or 6 h prior to the cycling trials, participants were treated with PBMT on the quadriceps, hamstrings, and gastrocnemius muscles of both limbs using a multi-diode array (11 cm × 30 cm with 264 diodes) at doses of 152 J or a sham irradiation (with device turned off, placebo). Blood samples were collected before and 30 min or 6 h after treatments to measure plasmatic nitrite concentrations. Doppler ultrasound exams of the femoral artery were also performed at the same time points. Cardiorespiratory responses, blood acid-base balance, and K+ and lactate concentrations were monitored during exercise sessions.ResultsPBMT did not improve the time to exhaustion (p = 0.30). At rest, no differences were found in the peak systolic velocity (p = 0.97) or pulsatility index (p = 0.83) in the femoral artery, and in plasma nitrite concentrations (p = 0.47). During exercise, there were no differences for any cardiorespiratory response monitored (heart rate, p = 0.15; oxygen uptake, p = 0.15; pulmonary ventilation, p = 0.67; carbon dioxide output, p = 0.93; and respiratory exchange ratio, p = 0.32), any blood acid-base balance indicator (pH, p = 0.74; base excess, p = 0.33; bicarbonate concentration, p = 0.54), or K+ (p = 0.22) and lactate (p = 0.55) concentrations.ConclusionsPBMT at 152 J applied 30 min or 6 h before cycling at severe-intensity did not alter resting plasma nitrite and blood flow velocity in the femoral artery, exercise-induced physiological responses, or time to exhaustion in healthy untrained men.