Experimental data have shown that the hind limb bones of frog experience variable magnitudes of strain even during jumps of similar performance. Studies of other species have shown that modifications of limb posture can influence the load magnitude and regime that bones experience. To test whether variations in limb kinematics might account for variation in bone loading during jumping in frogs, we collected high speed video of frogs Rana catesbeiana and toads Bufo marinus during jumps in which we simultaneously recorded bone strains, and regressed values of kinematic variables on strain magnitude. Despite a ten-fold range in strain magnitude in each species, no correlations were found between values of kinematic variables at peak strain (e.g., femur retraction, femur adduction, angles of the knee and ankle) and peak strain magnitude. This suggests that unlike other species previously examined (e.g., alligators), variation of strain magnitude is not influenced by limb position. Supported by NSF (IOB-0517340).
Available at: http://works.bepress.com/megan_sheffield/2/