Switching between walking and running seem natural to us but technically these are two different activities. Locomotion, which includes walking, jumping and
running is an important topic in biomechanics. Intense research in the field of gait analysis has helped orthopaedic medicine a great deal to not only to treat and cure but also to improve the designs of orthopaedic aids for the injured and the handicapped. Also
assumes great significance in sports medicine.
The movement of the centre of mass (COM) of the body, the
contribution from potential and kinetic energies and absence or presence of an airborne status these are the features that distinguish a Walk from a Run. During walking the COG moves in a curvaceous
manner from side to side akin to an inverted pendulum, as feet take turns to be
grounded and airlifted, there will be fleeting yet recurring moments when both
feet are on the ground, and potential and kinetic energy contributions are out
of phase. During running the COM is
bobbing up and down like a bouncing ball,
there are moments when the entire body is suspended in air, the potential
and kinetic energy contributions are in phase and the kinetic energy demands soar.
The same criteria hold good for
quadrupeds too.
While the fleeting airborne status during running is indeed a reality for humans or agile quadrupeds such as deer or tiger, could this be true for elephants too? Two teams one headed by
A complex proposition indeed. To understand the
complexity in its entirety, just have a
look at the animal itself.
A mature bull elephant could weigh as much as 5000kg and stand tall at a
3 meters. Give and take a 1000kg or a
meter depending on the generic and gender variations. Elephant legs are cylindrical columns,
in more precise terms load
bearing pillars; tall, fat and straight.
The feet circumference could range of 120-140 cm. The front foot is
quite circular in shape, and the rear a
bit oval. Composed mostly of elastic fibrous
tissue these are very efficient shock absorbers too.
.
To monitor the gait features of the heaviest animal on earth, Heglund and team decided to construct a test
rig at the Elephant Conservation Centre (ECC) in Lampang , Thailand Belgium
It must not have been easy to get the elephants walk over the desired path. They must have needed excessive coaxing by their mahouts. Even then instigating them to charge forward onto the test rig must have been no less than close encounter with danger.
Now to the results:
believe it or not the elephant is indeed a very very energy efficient animal. The team found out that the energy expenditure on locomotion for an elephant’s is 1/3rd that of humans and 1/30th that of
mice. Elephants take quicker
steps; ( high “step frequency”). At slow pace they have 3 feet grounded and in "faster mode " have two feet on ground. While this effectively keeps the COM displacement and hence energy requirements to a minimum, doesn't qualify for
running; because the mandatory airborne phase is absent. However energy diagrams recorded a slight vertical displacement of the
center of mass ( bouncing), characteristic of
trotting during the second half of the gait cycle!
Ha so the elephant walks as it trots!
Ha so the elephant walks as it trots!
1. Biomechanics of locomotion in Asian
elephants J Exp Biol 213, 694-706.2010, Genin et al
2. Integration of biomechanical compliance, leverage, and power
in elephant limbs Proc. Natl. Acad. Sci. USA 2010 107:7078-7082. Ren et al
