Patients with nonspecific chronic low back pain and pain equal to or greater than 3 in the Pain Numerical Rating Scale ( 0/10 ) will be randomly assigned to one of two groups : Group with active interferential current + Pilates ( n = 74 ) will be submitted to the active interferential current associated to the modified Pilates exercises , and Group with sham interferential current + Pilates ( n = 74 ) will be submitted to the sham interferential current associated with the modified Pilates exercises during 18 sessions .