Fig 1 -

The segment reference frames for the multi-segment foot model (left), marker set (center), and the two foot models (right). The SHANK reference frame was the same for both models and the single segment foot reference frame in SINGLE was the same as the RF reference frame in MULTI. The multi-segment foot model included three segments (RF = rearfoot, FF = forefoot, and TOE). In each reference frame, the red arrow indicates the x-axis, the green arrow indicates the y-axis, and the blue arrow indicates the z-axis. The labelled markers are those of the: M1B - base of the first metatarsal; M5H - fifth metatarsal head; T5—distal edge of middle phalanx of the fifth toe; M1H - first metatarsal head; and HAL—distal edge of the proximal phalanx of the hallux.