Low back pain in dance: Prevalence and associated factors

Introduction Low back pain (LBP) is a leading cause of disability worldwide. Dancers, who are often required to perform complex and repetitive movements of the spine, are thought to be vulnerable to LBP. However, there is limited available evidence concerning the prevalence, experience, impact, or factors associated with LBP in this population. Therefore, the overarching aim of this thesis was to investigate the prevalence and factors associated with LBP in dance. Methods This thesis consists of five discrete but interrelated studies. Study one systematically synthesises the available evidence for the prevalence of, and risk factors for, LBP and injury in dance populations. Studies two and three investigates the prevalence and risk factors for LBP in multiple pre-professional and professional contemporary dance and classical ballet cohorts. Lifetime prevalence of LBP is determined using a cross-sectional study design. Monthly prevalence, duration, and impact of LBP episodes are investigated prospectively. Multivariable logistic regression is used to examine for individual and demographic factors associated with LBP. Studies four and five investigate the interaction between dance, LBP, and spine kinematics. To do so, they employ three-dimensional motion analysis and a multi-segment spine marker set. Posture as well as clinical and functional movement tasks common in LBP assessment are examined in dancers and non-dancers with and without LBP. Results The systematic review supported that dancers appear vulnerable to the experience of LBP. However, due to the heterogeneous nature of available research, and an absence of multivariable statistical analysis, clarity regarding the prevalence and risk factors for LBP remains limited. The need for multi-site epidemiological studies that employ definitions sensitive to the nature of LBP and that use appropriate statistical methods to investigate risk factors for LBP within dance populations was identified. The cross-sectional study revealed 74% of pre-professional and professional dancers had a history of LBP. Prospectively, 52% of dancers experienced activity limiting LBP and 24% suffered from LBP that was chronic in duration. Prior experience of LBP preceded the experience of future episodes of LBP (adjusted odds ratio: 3.98; 95% confidence interval: 1.44, 11.00; p < 0.01). There was no association between personal or demographic factors and LBP. With respect to spine kinematics, female dancers presented with a flatter upper lumbar spine posture (p< 0.01, ηp2 = 0.15) in the sagittal plane and increased upper lumbar (p=0.04, ηp2=0.08) and lower thoracic (p=0.02, ηp2=0.09) frontal plane range of motion than non-dancers. However, there was no interaction between these measures and LBP. During walking gait, female dancers with recent LBP displayed a moderate reduction in transverse plane ROM for the lower lumbar spine (effect size (ES)=-0.65, 95% CI: -1.24, -0.06, p=0.03), and a moderate increase in lower thoracic transverse plane ROM (ES=0.62, 95% CI: 0.04, 1.21, p=0.04) compared to asymptomatic dancers. Conclusion Dancers are vulnerable to the experience of LBP. However, there is considerable variation in the time-course and impact of LBP episodes. History of LBP predicts future episodes, which supports that LBP is rarely limited to a single episode. Beyond this, the factors associated with LBP are complex and not easily discerned. With respect to movement, an altered movement strategy during walking gait suggests that female dancers with LBP may compensate for reduced mobility in painful regions by increasing mobility in other regions. However, these movement strategies are subtle, and the overall number of biomechanical differences was limited. Whether this indicates dance training protects against biomechanical changes normally associated with LBP, or suggests dancers are intrinsically different to non-dancers requires further consideration.