AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 5 771-R778, Copyright © 1992 by American Physiological Society
Energetic cost of locomotion in the tammar wallaby
R. V. Baudinette, G. K. Snyder and P. B. Frappell
School of Biological Sciences, Flinders University of South Australia, Adelaide.
Rates of oxygen consumption and blood lactate levels were measured in
tammar wallabies (Macropus eugenii) trained to hop on a treadmill. In
addition, the work required to overcome wind resistance during forward
locomotion was measured in a wind tunnel. Up to approximately 2.0 m/s,
rates of oxygen consumption increased linearly with speed and were not
significantly different from rates of oxygen consumption for a quadruped of
similar body mass. Between 2.0 and 9.4 m/s, rates of oxygen consumption
were independent of hopping speed, and between 3.9 and 7.9 m/s, the range
over which samples were obtained, blood lactate levels were low (0.83 +/-
0.13 mmol.min-1.kg-1) and did not increase with hopping speed. The work
necessary to overcome drag increased exponentially with speed but increased
the energy cost of locomotion by only 10% at the average speed attained by
our fast hoppers. Thus, during hopping, the energy cost of locomotion is
effectively independent of speed. At rates of travel observed in the field,
the estimated energy cost of transport in large macropods is less than
one-third the cost for a quadruped of equivalent body mass. The energetic
savings associated with this unique form of locomotion may have been an
important physiological adaptation, enabling large macropods to efficiently
cover the distances necessary to forage in the semiarid landscapes of
Australia.
