Fig 1.
On loose sand substrate, two representative high-speed video traces of toe motion during slow walking and running in the stance phase.
The traces started at touch-down when the 3rd toe touched the ground at 0% of the stance phase. In the slow walking and running trials, the mid-stance is at 50% of the stance phase, and the 3rd toe cleared off the ground at 100% of the stance phase.
Table 1.
The key gait parameters during slow walking and running on loose sand substrate.
Table 2.
The statistical analysis trials number of two individuals during walking and running gaits.
Fig 2.
The parameters of ostrich toe fixed posture.
Angle β between phalanges I and II of the 3rd toe, angle γ between the tarsometatarsus and phalanx I of the 3rd toe (MTP3 joint), Z the vertical displacement of the metatarsophalangeal joint, angel ω between the tarsometatarsus and the horizontal plane.
Fig 3.
Five ostrich toe posture models.
At touch-down (0 posture), mid-stance (50% posture), lift-off (100% posture), 25% and 75% of the stance phase corresponding to 25% posture and 75% posture.
Table 3.
Interphalangeal joint angle and displacement parameters of ostrich toes.
Fig 4.
The averages and one standard deviations of the six toe joint angles and the vertical displacement of the metatarsophalangeal joint (α, β, γ, θ, φ, ψ, z).
They correspond to A B C D E F G, respectively, over the stance phases for all slow walking (blue dotted line) and running trials (red solid line) on loose sand substrate. The angle decrease represents flexion, while the angle increase indicates extension.
Fig 5.
The averages and one standard deviations of the lateral (X-direction) and forward (Y-direction) displacements of the metatarsophalangeal joint and toenail.
XMTP, YMTP, XTN, and YTN correspond to A B C D, respectively, over the stance phases for all walking (blue dotted line) and running trials (red solid line) on loose sand substrate. In the axis of ordinates, positive numbers indicate the movement direction of the metatarsophalangeal joint toward the outside of ostrich feet, and negative numbers indicate the movement direction of the metatarsophalangeal joint toward the inside of the ostrich foot.
Fig 6.
The averages and standard deviations of the six toe joint angles (α, β, γ, θ, φ, ψ) and the vertical displacement of the metatarsophalangeal joint (z) at touch-down, mid-stance, lift-off and the ranges of motion during walking and running on loose sand substrate.
A statistically significant effect of gait pattern is indicated by an asterisk (P < 0.05).
Table 4.
Key indicators of phalangeal joint angles and displacement during walking and running gaits on loose sand substrate.
Fig 7.
The averages and standard deviations of the lateral and forward displacements of the metatarsophalangeal joint and toenail at the ranges of motion during walking and running.
A statistically significant effect of gait pattern is indicated by an asterisk (P < 0.05).
Fig 8.
The averages and one standard deviations of the six toe joint angles and the vertical displacement of the metatarsophalangeal joint (α, β, γ, θ, φ, ψ, z).
They correspond to A, B, C, D, E, F, and G over the stance phases for all walking trials on the sand surface (blue dotted line) and solid surface (red solid line). The angle decrease represents flexion, while the angle increase indicates extension.
Fig 9.
The averages and one standard deviations of the six toe joint angles and the vertical displacement of the metatarsophalangeal joint (α, β, γ, θ, φ, ψ, z).
They correspond to A, B, C, D, E, F, and G over the stance phases for all running trials on the sand surface (blue dotted line) and solid surface (red solid line). The angle decrease represents flexion, while the angle increase indicates extension.
Fig 10.
The averages and standard deviations of the six toe joint angles and the vertical displacement of the metatarsophalangeal joint at touch-down, mid-stance, lift-off, maximum, minimum and also the ranges of motion during walking and running between solid ground and sand surface.
Statistically significant effects of ground medium differences are indicated by an asterisk (P < 0.05).
Fig 11.
Particle velocity field under the ostrich toe plantar surface.
In walking and running, the particle velocity field of five toe postures (0 posture, 25% posture, 50% posture, 75% posture, 100% posture) during the stance phase.
Fig 12.
Particle force field under the ostrich toe plantar surface.
In walking and running, the particle velocity field of five toe postures (0 posture, 25% posture, 50% posture, 75% posture, 100% posture) during the stance phase.
Fig 13.
Ostrich toe footprints at different particle planes during the stance phase.
A In walking gait. B In running gait.
Fig 14.
The force of sand particles on ostrich toe posture during the stance phase.
A Horizontal force. B Lateral force. C Vertical force.