# Multi-Segmental Motion in Foot during Counter-Movement Jump with Toe Manipulation
###### Abstract  
Human toes are crucial for vertical jumping performance. The purpose of this study is to investigate the acute effect of hallux abduction manipulation on foot inter-segment kinematic alterations and plantar loading redistribution during the countermovement jump (CMJ). Thirteen participants were recruited to join in this experiment, for the collection of the foot inter-segment kinematics and plantar pressure data. During the take-off phase, the contact area presented a significant increase while the pressure-time integral decreased in the second metatarsal (M2), whilst the third metatarsal (M3) and fourth metatarsal (M4) decreased significantly in pressure-time integral with Toe-Manipulation (TM). During the landing phase, maximum force and peak pressure were smaller in the big toe (BT) after hallux abduction manipulation. HXFFA (hallux-forefoot angle) showed a greater pronation after manipulation in the frontal plane (0%-26% and 50%-100%) with \(p\) = 0.002 and \(p\) < 0.001. In the transverse plane, the smaller adductions were found during 62%-82% in take-off and 62%-91% in landing (\(p\) = 0.003 and \(p\) < 0.001). There was a redistributed plantar loading during the landing phase from the medial to lateral forefoot. However, a reduced hallux range of motion in the TM session was exhibited, compared to Non-Toe-Manipulation (NTM). h _article_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_supplementary_sup_supplementary_sup_sup_plementary_sup_sup_plementary_sup_sup_sup_plementary_sup_sup_sup_plementary  
produce more tactile contact forces [8; 9; 10; 11]. Further, the forefoot strike pattern in the barefoot condition showed a stronger longitudinal arch and intrinsic foot muscle, thus functionally improving the mass-spring mechanics of running by storing and releasing elastic energy during locomotion [8; 12; 13]. A recent study has shown that passive hallux adduction, such as wearing narrow-toed shoes, may have a passive tension on the abductor hallucis muscles, decreasing lateral plantar artery blood flow [14]. However, [PERSON] et al. [15] found participants with running shoes showed increased peak and total stance muscle activation of the intrinsic foot muscles. The previous studies have proven a converse effect of gait biomechanical performances in the lower limb from either acute or longitudinal hallux-related manipulation [6; 16; 17; 18]. A 12-week minimal footwear intervention redistributed plantar pressure during gait [6]. Acute toe manipulation increased the inter-segmental flexibility in the foot and laterally redistributed foot loading [18]. Also, an unstable structure under the hallux region may affect the gait and biomechanical performance and increase metatarsophalangeal joint flexibility through the stimulation of the toe gripping function [17]. Vertical jumping is a fundamental movement skill in human beings, which involves the coordination of multi-joint movement [19]. [PERSON] et al. [20] found that biomechanical assessment during the vertical jump could be used in athletic performance and injury prevention. Vertical jump performance based on morphology-related foot function and the importance of well-functioned toes was recognized while performing a basic jumping task. The contribution of the forefoot and toes has been evaluated while performing the vertical jump, with kinematics, kinetics, and spatiotemporal parameters being analyzed [4]. The toes functioned primarily in a prehensile and ambulatory way, in which the support-based area in the take-off and landing phase of locomotion was enlarged through the gripping action of five separated toes [5; 16].