Fig. 6. Motion analysis (blue) and inertial sensor (red) outputs for x, y and z displacements after high-pass filtering (mean ± S.D.). Data are shown for a stride at (A) walk (1.4 m s^-1), (B) trot (3.5 m s^-1) and (C) left lead canter (9.0 m s^-1). Smaller standard deviations (compared with the unfiltered displacements in Fig. 5), especially in the y direction, show that high-pass filtering is a valid means of eliminating non-cyclical inter-stride differences of the displacements.