INTRODUCTION: Chronic low back pain is a current society problem associated to pain sensations and high level of paraspinal muscle fatigability to exercise, which can be improved following a 4-week functional restoration program. These These symptoms could be related to an alteration in aerobic metabolism responses in regard of paraspinal muscles. The aim of this study was to evaluate the aerobic metabolism responses in regard of paraspinal muscles before and after a 4-week functional restoration program in chronic low back pain patients. METHODS: Twenty-two chronic low back pain patients were evaluated before and after a 4-week functional restoration program (11 men and 11 women; 41.6±1.8 years; 73.7±3.1 kg; 1.74±0.02 m). During both testing sessions, they performed the Sorensen test to evaluate paraspinal muscle fatigability. On another day, they performed a 5-minutes submaximal trunk extension exercise on an isokinetic dynamometer. A gas exchange analyzer and near infrared spectroscopy technique were used continuously to evaluate the on-set VO2 kinetics, the mechanical efficiency and the muscle oxygenation and blood volume to exercise. Before and after this exercise, pain sensations in the low back were evaluated using a visual analog scale. RESULTS: The holding time during the Sorensen Test was increased following the program (P<0.001). During the submaximal exercise the on-set VO2 kinetics was accelerated, the mechanical efficiency, the levels of muscle deoxygenation and blood volume were greater (P<0.05). Before the program, the 5-minute exercise induced an increase in low back pain sensations (P<0.05), whereas at the end of the program, the exercise did not induce an increase in pain sensations anymore (P<0.05). In addition, pain sensations were lower at the end of the program compared to before (P<0.05) CONCLUSION: The aerobic metabolism responses to specific exercise soliciting trunk extensor muscles were improved following a 4- week functional restoration program. It could permit to reduce the paraspinal muscle fatigability and the low back pain sensations induced by exercise.