Promoted Propulsion by Foot Windlass Mechanism in Jumping

As a result of millions of years of evolution, the modern human feet have unique and complicated structure compared to our primate relatives [1]. This unique configuration has been widely supposed to contribute to the bipedalism of modern humans [1]. A well-known feature of the modern human feet is the windlass mechanism [2] that includes plantar fascia, medial longitudinal arch, and metatarsophalangeal joints. In toe-off motion, the plantar fascia is stretched thus can pull the calcaneus towards the metatarsal heads [2] [3] [4]. Evidences from fossils suggested that this mechanism emerged in the past millions of years [5] [4], corresponding to the period when ancient human obtained the ability of durable bipedal locomotion [6]. Through the implementation of experiments on humans, several studies have focused on tendons and demonstrated that the elastic tendons contribute to restore and return the energy during stance phase (e.g. [7]). However, little attentions have been paid to the effects of the foot windlass mechanism on active power output.