The Relationship between Hamstring Flexibility, Lumbar Lordosis, and Daily Sitting Time among College Students: An Observational Cross-Sectional Study

Abstract

Background: Prolonged daily sitting, characteristic of college life, is associated with adaptive shortening of the posterior musculature — particularly the hamstrings — and may alter lumbar spinal curvature. Understanding the interplay between hamstring flexibility and lumbar lordosis in sedentary young adults is essential for developing evidence-informed preventive physiotherapy strategies. Objective: To investigate the relationship between hamstring flexibility, lumbar lordosis, and daily sitting time among college students aged 18–25 years. Methods: A cross-sectional observational study was conducted among 50 college students using convenience sampling. Hamstring flexibility was assessed bilaterally using the Straight Leg Raise (SLR) test. SLR values were classified as Severe (<45°), Moderate (45–69°), or Normal (≥70°). Lumbar lordosis was assessed in the relaxed standing position using the flexicurve ruler method and categorised as present or absent. The association between hamstring flexibility category and lordosis status was examined using the Chi-square test; between-group comparisons of SLR scores by lordosis status were performed using the Mann–Whitney U test; and bilateral SLR correlation was assessed using Pearson's r. Statistical significance was set at α = 0.05. Results: Mean bilateral SLR was 54.73° ± 17.37° (range: 30°–90°). The majority of students exhibited reduced hamstring flexibility: 42% Severe, 38% Moderate, and only 20% Normal. Lumbar lordosis was present in 24% of participants (n = 12). Students with lordosis had a marginally lower mean SLR (50.62°) than those without (56.03°), but the difference was not statistically significant (Mann–Whitney U, p = 0.329). Chi-square analysis revealed no significant association between hamstring flexibility category and lordosis status (χ² = 1.14, df = 2, p = 0.565). Bilateral SLR measurements were strongly correlated (Pearson r = 0.97, p < 0.0001), confirming measurement consistency. Conclusion: Reduced hamstring flexibility is highly prevalent among college students, with 80% exhibiting below-normal SLR values. Although a trend towards lower SLR in students with lumbar lordosis was observed, the association was not statistically significant in this sample, likely reflecting the multifactorial nature of lumbar curvature changes. The high burden of hamstring tightness in this population underscores the need for campus-based physiotherapy screening and targeted flexibility training programmes. Larger studies with quantitative measurements of lordosis are recommended.