The metabolic cost of walking on gradients with a waddling gait

Abstract

SUMMARYUsing open-flow respirometry and video footage (25framess -1 ), the energy expenditure and hindlimb kinematics of barnacle geese, Branta leucopsis, were measured whilst they were exercising on a treadmill at gradients of +7 and -7deg, and on a level surface. In agreement with previous studies, ascending a gradient incurred metabolic costs higher than those experienced on level ground at comparable speeds. The geese, however, are the first species to show an increased duty factor when ascending a gradient. This increased duty factor was accompanied by a longer stance time, which was probably to enable the additional force required for ascending to be generated. Contrary to previous findings, the geese did not experience decreased metabolic costs when descending a gradient. For a given speed, the geese took relatively shorter and quicker strides when walking downhill. This ʻchoppyʼ stride and perhaps a lack of postural plasticity (an inability to adopt a more crouched posture) may negate any energy savings gained from gravityʼs assistance in moving the centre of mass downhill. Also contrary to previous studies, the incremental increase in metabolic cost with increasing speed was similar for each gradient, indicating that the efficiency of locomotion (mechanical work done/chemical energy consumed) is not constant across all walking speeds. The data here suggest that there are species-specific metabolic responses to locomotion on slopes, as well as the established kinematics differences. It is likely that a suite of factors, such as ecology, posture, gait, leggedness and foot morphology, will subtly affect an organismʼs ability to negotiate gradients.

The metabolic cost of incline locomotion in the Svalbard rock ptarmigan (Lagopus muta hyperborea): the effects of incline grade and seasonal fluctuations in body mass

“…This method, however, relies on a difference between the regression slopes. In the present study, in common with findings in mice, crabs, quail and more recently geese, the MCoT did not differ upon incline locomotion in either season (Nudds and Codd, 2012;Taylor et al, 1972;Tullis and Andrus, 2011;Warncke et al, 1988). Applying the traditional approach to such data would therefore reveal no additional cost of lifting despite absolute energy expenditure values clearly being higher during incline locomotion.…”

“…Similar findings have been demonstrated in humans, although the curvilinear nature of metabolic cost during walking makes comparison with avian data problematic (Margaria et al, 1963). In the only avian studies to use solely walking gaits, quail on inclines of 4, 8 and 12deg shared a common slope and geese on inclines of 7deg showed no difference in MCoT compared with that on level ground (Nudds and Codd, 2012;Warncke et al, 1988). The results of both studies are in agreement with our findings, highlighting the importance of gait when measuring the energetic cost of locomotion.…”

“…Multiple data points at a single body mass represent the use of multiple grades in a single study. Data were taken from the literature for the following species: burro, Equus asinus (Yousef et al, 1972); caribou, Rangifer tarandus granti (Fancy and White, 1987); chimpanzee, Pan troglodytes (Taylor et al, 1972); cockroach, Periplaneta americana (Full and Tullis, 1990); crab, Ocypode quadrata (Tullis and Andrus, 2011); dog, Canis familiaris (Raab et al, 1976); elk, Cervus canadensis nelsoni (Cohen et al, 1978); goose, Branta leucopsis (Nudds and Codd, 2012); guinea fowl, Numida meleagris (Ellerby et al, 2003); horse, Equus caballus ; human, Homo sapiens (Margaria et al, 1963;Snyder and Farley, 2011;Yousef et al, 1972); kangaroo, Macropus rufus (Kram and Dawson, 1998); mouse, Mus musculus (Taylor et al, 1972;Snyder and Carello, 2008); button quail, Coturnix chinensis (Snyder and Carello, 2008); mountain quail, Oreortyx pictus (Snyder and Carello, 2008); quail, Coturnix coturnix (Warncke et al, 1988); rat, Rattus norvegicus (Snyder and Carello, 2008;Armstrong et al, 1983); reindeer, Rangifer tarandus groenlandicus (White and Yousef, 1978); sheep, Orvis aries (Clapperton, 1964); squirrel, Tamiasciurus hudsonicus (Wunder and Morrison, 1974); and stork, Leptoptilos crumeniferous (Bamford and Maloiy, 1980). metabolic cost across species of differing size, geometry and gait.…”

“…An increase in the MCoT with incline is expected only if efficiency (mechanical work/energy expended) is constant with changes in U (Nudds and Codd, 2012). However, this condition may not be a reality and could be affected by the changing mechanics and energetics associated with increasing U.…”

The metabolic cost of walking on an incline in the Peacock (Pavo cristatus)

“…Studies investigating the effects of incline locomotion on kinematic parameters have found differences in DF ( Dutto et al, 2004 ), stride frequency ( Gillis & Biewener, 2002 ) and t stance (the relative amount of time a foot is on the ground during a stride ( Hoyt, Wickler & Cogger, 2000 )) between level and incline locomotion. Force generation during t stance is a direct measure of the metabolic cost of locomotion, and stride frequency has been directly associated with energetic cost, yet relatively few studies have investigated the metabolic cost of incline locomotion with the associated kinematic changes ( Heglund et al, 1982 ; Lees et al, 2013 ; Nudds & Codd, 2012 ). Because the rate of force production is the parameter of interest, the inverse of contact time (1/ t stance ) is used for analysis and gives a measure of force application ( Kram & Taylor, 1990 ).…”