diana dennis's Profile

As the largest extant terrestrial animals, elephants do not trot or gallop but
can move smoothly to faster speeds without markedly changing their kinematics,
yet with a shift from vaulting to bouncing kinetics. To understand this unusual
mechanism, we quantified the forelimb and hindlimb motions of eight Asian
elephants (Elephas maximus) and seven African elephants (Loxodonta africana). We
used 240 Hz motion analysis (tracking 10 joint markers) to measure the
flexion/extension angles and angular velocities of the limb segments and joints
for 288 strides across an eightfold range of speeds (0.6-4.9 m s(-1)) and a
sevenfold range of body mass (521-3684 kg). We show that the columnar limb
orientation that elephants supposedly exemplify is an oversimplification--few
segments or joints are extremely vertical during weight support (especially at
faster speeds), and joint flexion during the swing phase is considerable. The
'inflexible' ankle is shown to have potentially spring-like motion, unlike the
highly flexible wrist, which ironically is more static during support. Elephants
use approximately 31-77% of their maximal joint ranges of motion during rapid
locomotion, with this fraction increasing distally in the limbs, a trend
observed in some other running animals. All angular velocities decrease with
increasing size, whereas smaller elephant limbs are not markedly more flexed
than adults. We find no major quantitative differences between African and Asian
elephant locomotion but show that elephant limb motions are more similar to
those of smaller animals, including humans and horses, than commonly recognized.
Such similarities have been obscured by the reliance on the term ;columnar' to
differentiate elephant limb posture from that of other animals. Our database
will be helpful for identifying elephants with unusual limb movements,
facilitating early recognition of musculoskeletal pathology.