Investigating the Role of Limb Asymmetry and Ground Reaction Forces of Quadrupedal Walking in Frogs

Many frog and toad species are specialized in jumping and swimming, credited to their short forelimbs and long hindlimbs. However, several frog species predominantly use walking or running as their primary mode of locomotion. The gait of these species is characterized by alternating diagonal forelimb and hindlimb pairs, allowing them to walk quadrupedally. Previous studies have found reduced length disparity between the fore- and hindlimb proportions in frogs specialized for walking and running, compared to species which predominately jump or swim. However, it remains unclear how this disparity in limb lengths impacts how force is produced between the fore- and hindlimb during a stride. In this study, we examine how three-dimensional forces applied between the fore- and hindlimbs differ across three walking frog species (Kassina senegalensis, Phrynomantis bifasciatus, and Phyllomedusa hypochondrialis). We used 3D high-speed videography to track ten joint centers along the forelimbs and hindlimbs during walking events across a force plate. Our preliminary findings show that the forelimbs of quadrupedal walking frogs exert a greater amount of force on the ground compared to the hindlimbs. The findings suggest that limb proportions have an impact on the force distribution during a stride. This research was supported by the National Science Foundation (NSF) under Grant Number BRC-BIO 223366 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.