Can photobiomodulation improve quadriceps strength and endurance outcomes in asymptomatic adults? A double-blind randomized controlled trial.

AIM: To explore the effect of photobiomodulation on quadriceps strength and endurance torques in asymptomatic adults. METHODS: Twenty-eight asymptomatic adults were randomized to one of two interventions: photobiomodulation (n = 14) or sham (n = 14). Quadriceps strength was evaluated by maximum voluntary isometric contraction test (60°) and endurance by an elastic resistance in multiple-set knee extension/flexion repetitions using a traction dynamometer. The outcomes were measured at three time points: pre-baseline; baseline and; final assessment. The photobiomodulation was applied to the quadriceps and triceps surae muscles of each participant's dominant lower limb, using a cluster with 1 infrared laser diode and 3 led amber of 170 mW for 240 s over four consecutive days. The sham group went through the same procedures, but the equipment was off, and patients and assessors were blinded to the intervention. Reliability and minimal detectable change of the measures were obtained from the pre-baseline and baseline time points. Differences between interventions were tested by an analysis of covariance. RESULTS AND DISCUSSION: There was no difference between photobiomodulation compared to sham in maximum isometric torque (mean difference (95% CI) = 0.008 (-0.29 to 0.31) and endurance torques (mean difference (95% CI) = 0.04 (-0.03 to 0.12). The mean difference was lower than the minimal detectable change for the maximum isometric torque (1.02 Nm.kg-1) and endurance torque (0.49 Nm.kg-1). CONCLUSION: Photobiomodulation does not improve quadriceps strength and endurance outcomes in asymptomatic adults.

Effect of photobiomodulation in the patellofemoral pain syndrome; randomized clinical trial in young women.

OBJECTIVE: patellofemoral pain syndrome (PFPS) is one of the most frequent musculoskeletal disorders in the knee joint, affecting mainly physically active adolescents and young adults; its main symptom is pain. Physiotherapy has several therapeutic modalities aimed at pain relief, among which are photobiomodulation (PBM). The aim of the study was to analyze the effects of using PBM in cluster form (Laser + LED) in patients with PFPS. PATIENTS AND METHODS: This study is characterized as quantitative, experimental, randomized, composed of 30 women with PFPS, randomized into two groups: Control Group (CG) and PBM Group (PBMG). Both groups underwent three evaluations: pre-intervention, post-intervention, and after one month of follow-up. Participants of the PBMG were presented to the application of the cluster device, three times a week, for four weeks. The intensity of spontaneous pain and movement were evaluated, knee function tests and function questionnaires. The results showed a reduction in pain only for the landing of the jump. As for the other variables there was no interaction of factors; the questionnaires used showed larger effect sizes for PBMG when compared to CG. It is possible to conclude that the use of PBM showed benefit in reducing pain at the time of landing of the jump and functional assessment questionnaires.