Effects of light-emitting diodes phototherapy on autonomic modulation of footballers

Abstract

The aim of the study was to analyze the effects of LED therapy during a training week on parasympathetic modulation and perceived stress in football players. Eigthteen soccer players participated in this study (Age: 21.2 ± 2.6 years; Body mass: 73 ± 7.2 kg; Stature: 178.0 ± 6.2 cm). Pre and post one training week rest heart rate and subjective perceived stress through daily analysis of life demands for athletes (DALDA) questionnaire was obtained. During this week the athletes were randomized in two groups: LED phototherapy (LED) and placebo (PLA). The treatment with LED phototherapy was applied on four points in lower limbs on quadriceps and hamstring muscles every day after the last training session. The treatment was performed in a doubleblind fashion. ANCOVA with repeated measures was applied to check the effects of treatment on autonomic modulation. The training performed by both groups was similar regarding intensity and duration. Likewise, there was no difference between groups for the internal load. We observed a time effect for the parameters mean RR intervals (RRmédio - LED: pre = 1033.4 ± 150.7 ms post = 1056.7 ± 114.8 ms; PLA: pre = 962 ± 15.8 ms post = 1016.8 ± 173.5 ms), standard deviation of the mean RR intervals (SDNN - LED: pre = 101 ± 37.3 ms post = 92.3 ± 27.5 ms; PLA: pre = 97.5 ± 34.9 ms post=108.7 ± 16.4 ms), e low and high frequency ratio (LF/HF- LED: pre = 1.7 ± 0.7 post = 1.4 ± 0.6; PLA: pre=3.7 ± 3.4 post=3.4 ± 2.1) for both groups. Furthermore, there were small changes in the sources (pre = 1 ± 1; post = 0 ± 1) and symptoms (‘better than normal’ pre = 5 ± 1; post = 4 ± 4; ‘normal’ pre = 19 ± 7; post = 21 ± 3) of DALDA for LED group. The LED phototherapy did not affect the autonomic modulation, but led to small changes in the perceived stress.