BRIEF REPORT Acute effect of photobiomodulation therapy on handgrip strength of chronic kidney disease patients during hemodialysis Fabrício Edler Macagnan 1 & Bruno Manfredini Baroni 1 & Érika Zanchet Cristofoli 2 & Marília Godoy 2 & Jociane Schardong 3 & Rodrigo Della Méa Plentz 1,3 Received: 16 January 2018 /Accepted: 16 July 2018 # Springer-Verlag London Ltd., part of Springer Nature 2018 Abstract 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. Keywords Phototherapy . Low level laser therapy . Muscle . Strength . Chronic kidney disease (CDK) . Chronic disease Introduction Chronic kidney disease (CKD) is a long-term metabolic con- dition that can need renal replacement therapy, such as hemo- dialysis (HD) or renal transplantation, to sustain life [1]. These patients have limited physical conditioning and many other health problems such as anemia, cardiac dysfunction, muscle abnormalities, and depression [1–3]. Even an effective HD therapy is not able to avoid some accumulation of HD metab- olites, which in turn lead to a persistent muscular atrophy (for more details, see Kouidi et al. [2]). CKD patients typically present low aerobic capacity with a significantly reduction in peak oxygen consumption, decreased strength, and reduced scores on functional tests (for review, see Koufaki et al. [3]). The negative impact on CKD prognosis impost by a low physical capacity can be significantly improved through spe- cific exercise programs [4]. CKD patients engaged in resis- tance training programs shown improvements in muscle quan- tity, quality, and oxygen extraction capacity [5]. Nonetheless, the poor health conditions of some CKD patients and the heavy hospital/ambulatory routines, especially for patients un- der HD, are usually associated with a modest adherence to these kinds of adjunct therapies [2]. Therefore, clinicians should be aware for new strategies and/or resources to im- prove the exercise tolerance during the HD periods. A single application of photobiomodulation therapy (PBMT) before exercise protocols has been shown to be * Fabrício Edler Macagnan fabriciom@ufcspa.edu.br 1 Graduate Program in Rehabilitation Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Sarmento Leite, 245, Porto Alegre, Rio Grande do Sul 90050-170, Brazil 2 Physiotherapy Course, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil 3 Graduate Program in Health Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil Lasers in Medical Science https://doi.org/10.1007/s10103-018-2593-7