The Association Between Hamstring Tightness and Chronic Low Back Pain: A Comparative Study

Introduction Chronic low back pain (CLBP) is defined as pain in the lower back that persists for more than three months. It is a common musculoskeletal condition and a major contributor to functional impairment and social limitations among young adults. Hamstring flexibility refers to the ability of the hamstring muscles to stretch to their full length. Since both the hamstrings and lumbar extensor muscles originate from the pelvis, a biomechanical relationship may exist between them. Decreased flexibility or weakness in these muscles may contribute to the development of low back pain. Tight hamstrings, which may result from previous injury or insufficient physical activity, can restrict pelvic mobility and limit movement of the lumbar spine. Such limitations may be associated with repetitive microtrauma, thereby contributing to the development of back pain. This study aimed to examine the association between hamstring tightness and CLBP. Materials and methods A cross-sectional analytical study was performed after obtaining ethical approval. The study included 40 patients diagnosed with CLBP and 40 age-matched healthy individuals who served as controls. Hamstring flexibility was evaluated using the active knee extension (AKE) test and the passive straight leg raising test (PSLRT), conducted on multiple occasions. Anthropometric parameters, including height, weight, and BMI, were also recorded. Statistical analysis of the collected data was carried out using the chi-square test and correlation analysis. The analysis was performed using SPSS version XX (IBM Corp., Armonk, NY). A p-value < 0.05 was considered statistically significant (α = 0.05). Pearson's correlation coefficient was used for normally distributed variables. Results Abnormal findings in the PSLRT were observed in 35 (87.5%) cases on the right side and 32 (80%) cases on the left side. In contrast, among the control group, only five (12.5%) individuals showed abnormal SLRT results on both sides. These differences were statistically significant (right: χ² = 45.00, p < 0.001; left: χ² = 36.10, p < 0.001). The AKE test revealed hamstring tightness on the right side in 35 (87.5%) cases compared to five (12.5%) controls, and on the left side in 33 (82.5%) cases compared to seven (17.5%) controls. These differences were also statistically significant (p < 0.001). The mean age of participants in the case group was 28.50 ± 5.48 years, while the control group had a mean age of 28.28 ± 5.11 years. Most participants were within the 20-40 year age range, a group in which mechanical low back pain is commonly seen. Both the AKE test and PSLRT indicated significantly reduced hamstring flexibility among individuals with CLBP compared to the control group. In addition, a positive correlation was identified between increased height and the presence of hamstring tightness. Conclusions The findings of this study suggest that individuals suffering from CLBP have significantly decreased hamstring flexibility compared to healthy individuals. The study also demonstrated an association between increased height and greater hamstring tightness in both case and control groups.