Acute Effect of Photobiomodulation Therapy in Quadriceps Strength, Fatigue and Pain of Patients With Chronic Kidney Failure: A Randomized, Double-blind, Placebo Controlled Crossover Clinical Trial

Background Patients with chronic kidney failure (CKF) present changes in physical capacity and low exercise tolerance. Photobiomodulation therapy (PBMT) has shown an ergogenic effect on exercise in studies with different populations and may be an adjuvant treatment in rehabilitation programs for CKF patients. This study aimed to evaluate the acute effects of different doses of PBMT on quadriceps strength, fatigue and muscle pain in CKF patients. Methods This study is a randomized, placebo-controlled, double-blind, crossover clinical trial. Adult patients with CKF received four PBMT applications with different energy doses (30J, 60J, 90J, or placebo), administered in a random order. A one-week interval was maintained between each dose, and an 830 nm laser was applied to six points of the quadriceps muscle. Immediately after PBMT, maximum isometric quadriceps muscle strength was assessed by dynamometry. Before the intervention and after the assessment of muscle strength, muscle fatigue (Borg rating of perceived exertion scale and blood lactate) and pain perception in the lower limbs (visual analogue scale) were measured. Results Fifteen patients were randomized and 14 completed the study. There was no significant difference between the doses tested for maximum isometric muscle strength in the right (p = 0.053) and left (p = 0.509) quadriceps. The perception of fatigue assessed by the modified Borg scale was not altered (p = 0.703) nor were blood lactate levels, regardless of the PBMT dose and measurement time (t0: p = 0.126; t3: p = 0.667; t6: p = 0.700). There was no change in pain perception after quadriceps irradiation for any of the PBMT doses tested (p = 0.566). Conclusion A single application of PBMT with a dose of 30J, 60J, or 90J did not alter maximum isometric quadriceps muscle strength, fatigue, or muscle pain perception in the lower limbs of CKF patients on HD.