Benefits of a four-week functional restoration program in chronic low back pain patients and three-month follow-up: focus on paraspinal muscle aerobic metabolism responses to exercise.

Background: Chronic low back pain (CLBP) is a major health concern characterized by paraspinal muscle fatigability. This can be improved following a functional restoration program. Muscle fatigability can be related to impairment in aerobic metabolism responses. In this study, we investigated paraspinal muscles aerobic metabolism in CLBP patients before and after a functional restoration program, in order to determine if the enhancement in patients' condition following the program is associated to changes in metabolism responses.

Methods: Twenty-two CLBP patients (11 women, 11 men; 41.6±1.8 years; 73.7±3.1 kg; 1.74±0.02 m) were evaluated before and after a 4-week functional restoration program, with exercise therapy as the main component. Three months later, 12 patients were seen for a follow-up visit. During each testing session, patients performed a five-minute isokinetic trunk extension exercise in measuring pulmonary gas exchanges and paraspinal muscle oxygenation. Mechanical efficiency and onset V̇O2 kinetics were also calculated, in addition to usual questionnaires and exercises designed to evaluate psychosocial and physical factors.

Results: At the end of the program, paraspinal muscle oxygenation, mechanical efficiency, and the V̇O2 onset kinetics were improved (P<0.05). All measures remained stable during the three-month follow-up except for paraspinal muscle oxygenation, which deteriorated (P<0.05). Return-to-work was associated with the level of workday physical activities and to a decrease in fear-avoidance beliefs.

Conclusions: At the end of the program, aerobic metabolism responses were improved in paraspinal muscles in patients. These improvements were not associated with return-to-work, which was primarily influenced by socio-psychological factors.