Size-related biomechanical constraints on foot impacts in ungulate mammals

Sharon Elaine Warner, Phillip Pickering, Olga Panagiotopoulou, Thilo Pfau, Lei Ren, John R. Hutchinson

Research output: Contribution to conferenceAbstract


Understanding the mechanics of foot impact and its
relationship with animal size may improve our ability to detect,
prevent and treat foot disease. Newtonian mechanical
principles suggest that heavier animals have a larger effective
foot mass (Meff); this may contribute to greater impact forces
that could initiate impact injury. So, for example, how can a
3000kg elephant safely control ~150kg of foot mass with every
step? We hypothesised that Meff is modulated to ensure impact
forces remain fairly constant in ungulates of increasing size.
Using standard force-platform (1000Hz; Kistler, 200Hz; AMTI)
and motion capture (250Hz; Qualisys or AOS high speed
camera) methods we measured limb kinematics and kinetics in
eleven species ranging from 18kg (blackbuck antelope) to
3157kg (Asian elephant). As ungulates get heavier, the forefoot
Meff exhibits surprisingly strong negative allometry at slow
running speeds; conversely, the hindfoot Meff has at least weak
positive allometry at walking speeds. Impact force amplitude
scales with isometry and peak GRF scales with negative
allometry at dynamically similar speeds. Curiously, increased
Meff is not reflected in the impact force amplitude, which
remains a fraction of the GRF peak. These mechanisms show
how ungulates keep impact amplitude from becoming a more
prevalent cause of impact injury.
Original languageEnglish
Number of pages1
Publication statusPublished - 2012
Externally publishedYes
EventAnnual Meeting of the Society-for-Integrative-and-Comparative- Biology (SICB 2012) - Charlestowon, United States of America
Duration: 3 Jan 20127 Jan 2012


ConferenceAnnual Meeting of the Society-for-Integrative-and-Comparative- Biology (SICB 2012)
Abbreviated titleSICB 2012
Country/TerritoryUnited States of America
Internet address

Cite this