Photobiomodulation Therapy Combined with a Static Magnetic Field Applied in Different Moments Enhances Performance and Accelerates Muscle Recovery in CrossFit® Athletes: A Randomized, Triple-Blind, Placebo-Controlled Crossover Trial

Abstract

The ergogenic effects of photobiomodulation therapy combined with a static magnetic field (PBMT-sMF) on exercises with characteristics similar to those of CrossFit® are unknown. This study was aimed at investigating the effects of PBMT-sMF applied at different times on recovery and physical performance in CrossFit® athletes by analyzing functional aspects, muscle damage, inflammatory processes, and oxidative stress. This was a prospectively registered, triple-blinded, placebo-controlled, crossover trial. CrossFit® athletes were recruited and assigned to receive one of the four possible interventions. Each intervention included protocols before and after the exercise (referred to as the workout of the day (WOD)). The four possibilities of intervention were as follows: placebo before and after WOD (placebo), PBMT-sMF before and placebo after WOD (PBMT-sMF before), placebo before and PBMT-sMF after WOD (PBMT-sMF after), and PBMT-sMF before and after WOD (PBMT-sMF before and after). The order of possibilities for the interventions was randomized. The primary outcome was the functional test performance. The secondary outcomes were the subjective perception of exertion, muscle damage, inflammation, and oxidative stress. The outcomes were measured before the WOD; immediately after the intervention; and 1, 24, and 48 hours after the WOD. Statistical analysis was performed using repeated measures ANOVA followed by the Bonferroni post hoc test to examine the differences between the interventions at each time point. Twelve participants were randomized and analyzed for each sequence. PBMT-sMF enhanced the performance on functional tests (calculated as a percentage of change) when applied before or after WOD in the assessment performed immediately post-WOD and at 24 and 48 hours later ( p < 0.05 ) compared to placebo and PBMT-sMF before and after WOD. In terms of the secondary outcomes, PBMT-sMF applied before or after WOD significantly decreased the creatine kinase, catalase, and superoxide dismutase activities and interleukin-6, thiobarbituric acid, and carbonylated protein levels (all p < 0.05 ) compared to the other possibilities of intervention. In addition, PBMT-sMF applied before and after WOD decreased creatine kinase activity at 24 hours and IL-6 levels at 24 and 48 hours compared to placebo ( p < 0.05 ). None of the participants reported any adverse events. PBMT-sMF enhanced the performance of functional tests, decreased the levels of biochemical markers of muscle damage and inflammation, decreased oxidative stress, and increased antioxidant activity in CrossFit® athletes when applied before or after WOD.

Can Photobiomodulation Therapy (PBMT) Minimize Exercise-Induced Oxidative Stress? A Systematic Review and Meta-Analysis

“…These studies were published between 2011 and 2022. Six trials included studies that performed crossover designs [ 35 , 36 , 37 , 38 , 39 , 40 ], and two were parallel trials [ 41 , 42 ]. The characteristics of the study can be found in Table 1 .…”

“…PBMT parameters and application of all studies are shown in Table 2 . Only one article performed a protocol of exercises applying PBMT on the upper limbs [ 41 ]; the other authors performed a protocol on the lower limbs [ 35 , 36 , 37 , 38 , 39 , 40 , 42 ]. Seven articles [ 35 , 36 , 37 , 38 , 39 , 40 , 42 ] carried out the application of PBMT before exercising (3 min and 40 min); and two studies [ 40 , 41 ] were carried out from 2 min after exercise.…”

“…Jówko et al [ 37 ] performed 45 isometric contractions associated with transcutaneous neuromuscular electrical stimulation (NMES) in the quadriceps muscle. Pinto et al [ 40 ] submitted their participants to CrossFit ® training sessions, consisting of a sequence (21 repetitions, 15 repetitions and 9 repetitions) of three exercises (pedalling the Assault AirBike ® , Hang Squat Clean and Box Jump Over). Meanwhile, Leal-Junior et al [ 39 ] performed the Wingate test on a cycle ergometer at maximum velocity for 30 s, using a load equivalent to 7.5% of athlete body mass.…”

“…The most frequent oxidative stress biomarkers were carbonylated proteins (CP), damage to lipids [malondialdehyde (MDA) and thiobarbituric acid reactive substances (TBARS)], in 75% and in all studies, respectively. The catalase (CAT) was analyzed for four studies (50%) [ 38 , 40 , 41 , 42 ], and superoxide dismutase (SOD) for five trials [ 35 , 37 , 38 , 40 , 42 ]. Other biomarkers measured were glutathione peroxidase (GPx) and total antioxidant capacity (TAC) [ 37 ].…”

“…Other biomarkers measured were glutathione peroxidase (GPx) and total antioxidant capacity (TAC) [ 37 ]. The time-points analyzed after exercise in the articles reporting trials were: 100% ( n = 7) immediately after physical exercise (0–5 min) [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ]; 38% ( n = 3) 1 h after physical exercise [ 35 , 40 , 42 ]; 50% ( n = 4) 24 h after [ 37 , 40 , 41 , 42 ]; 63% ( n = 5) 48 h after [ 36 , 37 , 41 , 42 ]; 38% ( n = 3) 72 h after [ 37 , 41 , 42 ]; and only 25% ( n = 2) 96 h after exercise [ 37 , 42 ].…”