Quadriceps femoris performance after resistance training with and without photobiomodulation in elderly women: a randomized clinical trial

The study assessed if quadriceps femoris muscle performance of older women can be improved by applying photobiomodulation therapy after a resistance training program. This study is a randomized, controlled trial with concealed allocation, intention-totreat analysis, and blinded outcome evaluators. Forty-five healthy sedentary older women classified as active or insufficiently active were randomized to groups receiving 8 weeks of quadriceps femoris resistance training plus active group or placebo group, or a control group (no training or photobiomodulation). Surface electromyographic fatigue indexes of vastus medialis, rectus femoris, and vastus lateralis; one-maximum repetition (1-MR); and analysis of inflammatory biomarkers (IL-6, IL-8, and TNF-a cytokines, plus CK and LDH enzymes) were measured at baseline and twice in a 24 h-period after 8 weeks. No differences among the three groups were found in fatigue indexes for all three muscles, although in general, the active group presented improved fatigue indexes from baseline to 8-week outcome, while the other groups did not. Both training groups improved in 1MR over the 8-week period. Inflammatory biomarkers were not different at long- or short-term among the three groups, except differences in groups for long-term IL-8 changes, differences in time for long-term LDH and short-term TNF-a changes, and interactions of time by group for short-term LDH changes. Quadriceps femoris performance of older women was not improved when photobiomodulation was associated to the proposed quadriceps femoris resistance training, when compared to training without photobiomodulation and a sedentary group.