Fig. 3. Gait, force, velocity and energy of the COM vs time during one stride of a 3.6 g (0.035 N) gecko Hemidactylus garnotii climbing vertically at 0.44 m s^-1. (A) Tracing of gecko climbing. Yellow circles represent foot contact. (B) Gait pattern and timing of attachment and release for each foot. The initial striped portion of each box represents the time required for the toe pads to attach to the force plate. The filled portion indicates when toe pads were in contact with the force plate, and the second striped portion represents the time for the toes to detach before the foot was lifted from the force plate. (C) Fore–aft, normal and lateral forces of the COM. The horizontal broken line represents weight (35 mN). Force production decreased nearly to zero at mid-stride, despite the fact that all four feet were in contact with the force plate. (D) Fore–aft velocity calculated by integration of the force recording minus gravity. Velocity attained a minimum at the beginning of each step as forces decreased to zero, indicative of a period of ballistic movement. (E) Fore–aft kinetic, normal kinetic, lateral kinetic energy (E_K) and gravitational potential energy (E_P) fluctuations of the COM. (F) Total mechanical energy of the COM obtained by summation of the fore–aft kinetic, normal kinetic, lateral kinetic and gravitational potential energy components.