Effects of Fatigue on Inter-joint Coordination in Ballet Dancers During a Ballet Jumping Movement (petit échappé sauté)

To examine the effects of fatigue on inter-joint coordination during repeated ballet jumping (petit echappe saute). Twenty female ballet dancers performed petit echappe saute movements up to and beyond the point of fatigue. The petit echappe saute movement and the hip-knee joint and knee-ankle joint coordination in the non-dominant leg was evaluated across the six sub-phases using a continuous relative phase measure. The six sub-phases were classified as follows: Phase1: initial takeoff phase from 1st position, Phase 2: the top of center of mass (COM) position from 1st to 2nd position, Phase 3: the terminal landing phase to 2nd position, Phase 4: initial takeoff phase from 2nd position, Phase 5: the top of COM position from 2nd to 1st position, and Phase 6: the terminal landing phase to 1st position. Phase deviations were used to quantify the movement pattern and inter-joint coordination variability, where larger deviation values meant a more variable relationship between the two joints. The dancers exhibited greater phase deviations during landing at a wider base of support, but a lower phase deviation at a narrower base of support following fatigue. The dancers showed less consistent inter-joint coordination between the hip and knee and between the knee and ankle following fatigue during phases 2 and 5 (airborne phase) and phase 4 (lowest center of mass phase). The present results suggest that the inter-joint coordination deteriorated during relatively difficult phases, and this change may put dancers at risk for injury.