Assessment of Asymmetrical Lower Limb Range of Motion in Six-Step, a Basic Footwork in Breakdance (Breaking)

Introduction: Six-step is the most fundamental footwork skill in breakdancing (breaking), commonly performed across skill levels and characterised by lower body rotation while landing dancers' hands on the floor. Interlimb asymmetry in dance poses a recognized injury risk, and the potential impact of Six-step that depends on the dancer's axis side and direction of rotation should be considered. However, the detailed kinematics of this process have not been fully investigated. This study aimed to determine the side-to-side differences in the lower limb range of motion (ROM) required during a Six-step execution. Methods: This cross-sectional study assessed 10 breakdancers using a marker-less motion capture system. The maximum hip and knee ROM on both the axial and non-axial sides during the Six-step cycles were quantified. The ROM values between the corresponding joints were compared, and the correlations between the ROM of the hip and knee were analysed. Results: The axis limb exhibited significantly greater ROM in hip adduction and knee flexion than the contralateral limb (20.3° ± 8.4° vs. 9.2° ± 4.3° and 152.8° ± 3.4° vs. 142.0° ± 5.1°; P = 0.006 and 0.002, respectively). The knee flexion ROM on the axis side significantly correlated with the ipsilateral hip adduction and internal rotation ROM. Conclusion: The Six-step procedure requires asymmetrical maximum lower limb ROM, with greater hip adduction and knee flexion demands on the axial side. Moreover, on the axial side, hip adduction and internal rotation are coupled with knee flexion, concurrently requiring a large ROM. The implications of asymmetrical ROM demand warrant further investigation.