Light-emitting diodes (LED) therapy applied between two running time trials has a moderate effect on attenuating delayed onset muscle soreness but does not change recovery markers and running performance

The study aimed to examine the recovery/performance effects of LED therapy applied between two running time trials on blood lactate, creatine kinase (CK), delayed onset muscle soreness (DOMS) and heart rate variability (HRV) in physically active participants. Eleven healthy and young males (26.7±4.8 years) volunteered to participate. Visits in the laboratory were divided into two phases (i.e., two different weeks with four visits each) using the same exercise protocols, but differing randomly in recovering intervention conditions: placebo (PLA) or LED therapy (LED). The minimal and maximal duration for each phase was one and two weeks. On the first day of each phase, the participants performed two (test 1 and test 2) time trials of 40-minute duration with six hours of interval separating the trials. Blood lactate, CK, DOMS, HRV were used as recovery measurements. Variables were compared using two-factor ANOVA for repeated measures followed by the Bonferroni post-hoc test for multiple comparisons. Cohen's effect size (ES) was used to estimate the magnitude of the difference. We found that LED therapy had a moderate ES on decreasing how much DOMS increased before test 2, despite no significant effect of LED therapy on CK, lactate concentrations, DOMS and parasympathetic activity (i.e., HRV). No influences were observed in endurance running performance (i.e., mean velocity in the 40-minute time trial). Results suggest LED therapy applied between two running time trials has a moderate effect on attenuating delayed onset muscle soreness but does not change recovery markers and running performance. Cette étude visait à évaluer les effets sur la récuperátion et la performance de la thérapie par diode électroluminescentes (DEL) appliquée entre deux essais chronométrés en course à pied sur lactatémie sanguine, la créatine kinase (CK), les douleurs musculaires différées (DOMS) et la variabilité de la fréquence cardiaque (HRV) chez des participants physiquement actifs. Onze jeunes hommes (26,7±4,8 ans) apparemment en santé se sont portés volontaires. Les visites au laboratoire ont été réparties en deux phases en utilisant les mêmes protocoles, mais en alternant les conditions de récupération: placebo (PLA) ou thérapie DEL (DEL). La durée entre chaque phase variait d’une à deux semaines. Durant la première journée de chaque phase, les participants ont effectué deux essais chronométrés d’une durée de 40minutes (tests 1 et test 2) avec une pause de six heures entre les