Association between posterior thigh tightness and lifetime low back pain in young basketball players: a cross-sectional study

Low back pain (LBP) is common in young athletes and may restrict participation in basketball. Evidence regarding the association between lower extremity tightness and LBP in adolescent basketball players remains limited. This study aimed to examine whether anterior (quadriceps) and posterior (hamstring) thigh tightness were associated with LBP in elementary and middle school players. In this cross-sectional study conducted in Fukushima, Japan (2013–2014), players completed questionnaires on the presence or absence of lifetime and point prevalence of LBP. Physiotherapists assessed mechanically provoked LBP (induced by lumbar flexion and extension), as well as anterior and posterior thigh tightness. Anterior thigh tightness was defined as a heel-buttock distance (HBD) > 0 cm, and posterior thigh tightness as a sit-and-reach (SR) value below the age- and sex-specific mean − 1 standard deviation (SD). Multivariable logistic regression was used to examine the association between anterior and posterior thigh tightness and lifetime LBP, adjusting for school level, sex, training days per week, years of play, current knee pain, and body mass index. Statistical significance was set at p < 0.05. Of the 385 participants, 324 players (mean age: 11.1 years; 39.8% male) were included in the analysis. The lifetime prevalence of LBP was 19.8%, the point prevalence was 4.6%, and the prevalence of LBP with lumbar extension and flexion were 15.7% and 4.0%, respectively. Anterior and posterior thigh tightness were present in 68.8% and 44.8% of players, respectively. In univariable analyses, players with posterior thigh tightness had higher prevalences of lifetime and current LBP and more frequently required rest from play. Multivariable analysis showed that posterior thigh tightness was independently associated with lifetime LBP (odds ratio: 2.11; 95% confidence interval: 1.07–4.15). In contrast, anterior thigh tightness was not significantly associated with LBP (odds ratio: 0.82; 95% confidence interval: 0.40–1.68). Posterior thigh (hamstring) tightness was independently associated with lifetime LBP in young basketball players. Longitudinal studies are needed to determine temporality and causality.