Mechanical determinants of axis drift and rotational speed in figure skating jumps.

Rotational jumps are a key technical element in figure skating. Jumps with a higher number of rotations require both a stable rotational axis and higher rotational speed. However, the determinants of these requirements remain unclear. This study aims to identify the primary determinants of the reorientation of the rotational axis and rotational speed. These variables were formulated based on rigid body mechanics to identify their determinants. The formulae were then applied to on-ice jump data to identify the primary determinants among them. We report that the primary determinant of the motion of the rotational axis was the angle between the angular momentum vector and longitudinal principal axis of inertia of the body; meanwhile, that of the rotational speed was the principal moment of inertia about the longitudinal principal axis of inertia of the body. In conclusion, the primary determinant of the motion of the rotational axis in figure skating jumps differs from that of the rotational speed. Thus, skaters must adopt a strategy for each to achieve both a stable rotational axis and higher rotational speed. This study clarifies the theoretical background of figure skating jumps.