Locomotion efficiency of elephants: mechanical work and energetics

Understanding how large terrestrial animals manage the energetic demands of locomotion remains a major question in biomechanics. Although smaller animals have been well studied, data on species exceeding 1 ton are scarce, making it difficult to evaluate whether principles derived from small and medium-sized species hold at the upper limits of body size. In this study, we examined the mechanical work of locomotion in 27 Asian elephants (872-4000 kg) across a large range of speed of progression. We quantified the internal work required to move the limbs relative to the whole-body centre of mass (COM) and combined it with external work to estimate total mechanical cost. Our results show that elephants devote a surprisingly large proportion of total mechanical work - up to ∼75% at higher speeds - to move the limbs. This highlights the importance of internal limb dynamics in shaping the energetic profile of large quadrupeds. Using published metabolic cost values for elephants, we estimate that their muscular efficiency during locomotion ranges between ∼30% and 45%, values that fall within the range reported for other large mammals such as horses and humans. Together, these findings offer the first detailed breakdown of internal and external mechanical work in elephant locomotion and provide novel insights into how extreme body size influences the partitioning of mechanical work. This study contributes new data essential for understanding locomotor energetics at the upper limits of terrestrial animal mass.