Meeting Abstract

P3.167  Sunday, Jan. 6  How toads minimize torques to stick their landings RANA, P.V.*; LARSON, N.P.; ABBOTT, E.M.; AZIZI, E.; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine ranapv@uci.edu

The task of landing after a jump requires motor control strategies that allow muscles to effectively dissipate energy and control posture to stabilize the body. Toads are exemplary models for understanding the mechanics and motor control of landing given their ability to land consistently during bouts of hopping. Previous studies in anurans have shown that ground reaction forces (GRF) during landing are significantly higher compared to take-off and can therefore destabilize the body at impact. To “stick” the landing, toads must minimize torques acting about their center of mass (COM) in order to avoid excessive body rotation and provide time for their forelimbs to dissipate mechanical energy. We predict that flexion of the hindlimbs during the aerial phase and in anticipation of impact functions to change the position of the COM and minimize torques during landing. To test this hypothesis we first quantify the location of the COM at hindlimb positions ranging from fully flexed to fully extended in anesthetized Cane toads (Bufo marinus). We then quantify ground reaction forces during landing using a three-axis force plate and quantify posture during landing using high-speed video. We use GRF data and the instantaneous position of the COM to calculate peak torques during landing. We find that hindlimb flexion during the aerial phase moves the COM anteriorly and reduces torques at the COM. Therefore, we conclude that toads are actively shifting their center of mass to reduce torque and stabilize the body during landing. Supported by NSF grant 1051691.