INTRODUCTION: Lumbar pain syndrome is one of the most widespread public health problems, and epidemiological studies prove that approximately 80% of the global population will experience back pain at some point in their lives. The mean global one-year prevalence in the adult population is about 37%, with it being more common in middle-aged and women. OBJECTIVE: To investigate the strength level of flexors and extensors and the endurance index of hip flexors and extensors in patients with lumbar pain syndrome. The specific objectives of the research are to compare the level of strength and endurance index of hip flexors and extensors with the same parameters in a healthy population, and to compare the level of strength and endurance index of hip flexors and extensors in subjects with lumbar pain syndrome regarding the sex of the subjects. METHODS: 30 patients with lumbar pain syndrome were included in the experimental group, while 30 subjects from the healthy population were included in the control group. Strength and endurance testing was performed on the "Cybex" isokinetic system, HUMAC NORM model, at the Clinic for the Treatment, Rehabilitation and Prevention of Cardiovascular Diseases, Thalassotherapy Opatija - Department of Physiatry. Statistical data processing was performed in the Statistica program (Version 13.5.0.17, 1984-2018 TIBCO Software Inc) using the non-parametric Wilcoxon rank sum test. RESULTS: Average hip flexor strength in subjects with lumbar pain syndrome was 59.3%, while average extensor strength was 99.9%. The average values of the hip flexor endurance index in subjects with lumbar pain syndrome were 8.5, while the average values of the extensor endurance index in the same subjects were -70.3. Hip flexors and extensors were stronger and more durable in the healthy population, compared to subjects with lumbar pain syndrome. Statistical data processing did not prove significant differences in the strength and endurance of hip flexors and extensors in subjects with lumbar pain syndrome, regarding gender. CONCLUSION: The strength and endurance of hip flexors and extensors can be seen as a predictor of lumbar pain syndrome, if they indicate an imbalance of one muscle group against another.