Meeting Abstract
P1.94 Tuesday, Jan. 4 The Energetics of Bipedal Locomotion Over Uneven Terrain CHANNON, A J*; DALEY, M A; Royal Veterinary College, UK; Royal Veterinary College, UK achannon@rvc.ac.uk
The mechanics of animal locomotion over flat level terrain is well understood, but our understanding of the way that animals move over unpredictable or pertubatory ground remains limited. Previous studies have identified both active (requiring central nervous system, CNS, input) and passive (independent of CNS involvement) mechanisms for stabilising the centre of mass while negotiating obstacles. There are likely increases in the metabolic cost of locomotion when negotiating uneven terrain associated with performing or absorbing mechanical work and stabilising the centre of mass to prevent a fall. Further costs are likely incurred by the reduced effectiveness of mechanisms traditionally thought to save energy, such as the breakdown of spring mass mechanics and abandonment of regular gait patterns. These additional costs are currently unknown and are unaccounted for in our current locomotion cost models. Here we present estimates of energy expenditure from common pheasants (Phasianus colchicus), as they negotiated obstacles of varying height while running on a treadmill. The pheasant’s mechanical energy cost was estimated using kinematic data while the metabolic cost of obstacle negotiation was attained using flow through respirometry. We show that the mechanical cost of negotiating the terrain increased approximately four fold with obstacle height, but the metabolic cost increased substantially less over the same increase in obstacle height. Further, the approach used by the birds to safely traverse the obstacles varied with obstacle height, with smaller obstacles effectively absorbed by adopting a more crouched posture during the obstacle step, requiring negligible extra mechanical work, while scaling larger obstacles required a increase in potential energy of the centre of mass and hence more mechanical work.
