The time-continuous association between turnout and axial joint moments in the competitive Irish dance 'fly' landing

Turnout is a key technical and aesthetic element in competitive Irish dance involving external rotation of the lower limb and must be sustained during landings. 'Forced' turnout, aided by floor friction rather than active hip rotation, is likely to result in large internal rotation moments at the knee and ankle, which may increase the risk of injury. The aim of the current study was to establish the relationship between the hip and ankle external rotation vector field and maximum internal rotation moments of the ankle and knee. Thirteen (12 female) competitive Irish dancers performed 10 flys (common Irish dance leap) onto a force plate while being recorded by a ten-camera motion capture system. Time-continuous data were analysed over the duration of landing using statistical parametric mapping (SPM). A positive correlation (p < 0.05) was found between the hip-ankle turnout vector field and maximum ankle internal rotation moments throughout most of the landing. Post-hoc analyses showed that hip external rotation contributed the most to the maximum ankle internal rotation moment (p < 0.05). Increasing hip turnout during landing could reduce internal rotation moments, assuming hip turnout brings the thigh and foot axial orientation more in line with each other.