Effects of Different Exercise Programs Plus Photobiomodulation on Non-specific Low-back Pain.

Inclusion Criteria: * Men and women aged 18-75 years * Self-report of recurrent (≥ 3 x/week) or continuous episodes of nonspecific low back pain for at least 3 months, comprising the lumbar region between L1-L5 Exclusion Criteria: * To present a history of musculoskeletal disorders that could affect muscle function * To make use of medicines that could affect muscle function. * To present low back pain of specific etiology, such as: tumor, herniated disc, facet syndrome, canal stenosis, among others. * To have used ergogenic supplements and anabolic steroids for at least six months before study * To present severe skin diseases in the lumbar region, such as: erysipelas, eczema, dermatitis, psoriasis and urticaria * To have restrictions for exercises practice considering Physical Activity Readiness Questionnaire (PAR-Q) responses.