49 obese patients suffering from chronic low back pain (cLBP) were randomized to receive resistance exercise (TOTRX), lumbar extensor exercise (LEXT), or to a control group (CON), in order to investigate the role of lumbar muscle strength on walking endurance. Patients were monitored over 4 months. The evidence presented in this study demonstrated greater gains in lumbar extensor strength after 4 months with the exercise groups compared to control. Responders (those with at least a 20% improvement in lumbar extensor strength) to resistance exercise (TOTRX) and lumbar extensor exercise (LEXT) reported better improvement in maximal walking speed.