This study will be conducing in a large hospital that is reference in Coronary artery bypass surgery. 15 patients will be randomized for placebo or low-level laser therapy (LLLT). The functional capacity will be test by test six-minute walk test before and after de LLLT. Moreover the application of LBP or placebo will be followed by assessments of muscle damage and oxidative stress. One-week interval between the LLLT will gave to reduce the influence between the treatments.