Acute effect of photobiomodulation therapy on handgrip strength of chronic kidney disease patients during hemodialysis

Pre-exercise photobiomodulation therapy (PBMT) reduces fatigue and enhances performance in different populations. However, PBMT benefits have never been tested on chronic kidney disease (CKD) patients, who present muscle weakness, fatigue, and reduced functional performance. The objective of this study was to evaluate the acute effect of three different doses of the PBMT on maximal handgrip strength of CKD patients. Fifteen volunteers (58 ± 8 years, 10 male/5 female) under chronic hemodialysis treatment (6 ± 4 years) participated in a randomized, crossover, double-blind, placebo-controlled trial. Each patient was assessed at four hemodialysis sessions with 1 week interval between evaluations. Placebo or PBMT (cluster probe with five 850 nm/200 mW laser diodes) were applied at three sites along the flexors of the finger (total doses of 60, 90, or 120 J per arm). The maximal handgrip strength was evaluated before and after PBMT/placebo treatment in each session. Repeated measures ANOVA and intraclass correlation coefficients (ICC) confirmed no learning effect on handgrip tests, and high scores for test-retest reliability (ICC scores = 0.89 to 0.95). Significant strength increases occurred after PBMT application with doses of 60 J/arm (4.85%, p = 0.005, ES = 0.32) and 90 J/arm (4.45%, p = 0.013, ES = 0.25), while no changes were detected with placebo or 120 J/arm. In conclusion, in consensus with a recent systematic review, a single bout of the 60 J/arm was the best dose/response for increased strength of the small muscles (handgrip strength). In view of the increasing implementation of exercise programs during hemodialysis, the current study opens a new field for PBMT for CKD patients.