Figure 3.

Passive Movements of the Locust Femur Tibia Joint Can Be Faster Than Active, FETi-Driven Movements

(A) Passive extensions from three different flexed starting positions. Movements are shown in black; velocities are shown in gray. Upon release (at 0.1 s), the tibia extended toward the resting position. Each curve describes a single trial, and comparable symbols indicate the movement and velocity of the same trial. The dashed line indicates a velocity of 0°/s.

(B) Velocities of passive movements differed markedly for different starting angles. Values are mean (±SD) peak velocities of passive tibial movements from seven animals. Positive velocities refer to flexions; negative velocities refer to extensions. The dotted lines connect the extension and flexion data sets for each individual animal. Within this central part of the joint angle range near the normal resting position, the tibia did not move when it was released.

(C) Passive extensions or flexions starting from extreme angles were, with one exception, faster than active, FETi-driven extensions starting at the central resting angle. The gray bars show the mean velocity over seven animals, and the symbols joined by black lines show the individual mean peak velocities for each animal separately. Passive extensions from full flexion were significantly faster than active extensions driven by single FETi spikes starting from the resting angle. There was no significant difference between the velocity of active extensions from the resting angle and passive flexions starting from extended angles. Insets show the starting position of the tibia (black) relative to the femur (gray) and the direction of resulting movement (curved arrows).

See also Figure S3.