Energetics of ascent: insects on inclines

1990 ◽  
Vol 149 (1) ◽  
pp. 307-317 ◽  
Author(s):  
R. J. Full ◽  
A. Tullis
Keyword(s):  
Oxygen Consumption ◽  
Minimum Cost ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Incline Angle ◽  
Small Animals ◽  
Cost Of Locomotion ◽  
The Cost

Small animals use more metabolic energy per unit mass than large animals to run on a level surface. If the cost to lift one gram of mass one vertical meter is constant, small animals should require proportionally smaller increases in metabolic cost to run uphill. To test this hypothesis on very small animals possessing an exceptional capacity for ascending steep gradients, we measured the metabolic cost of locomotion in the cockroach, Periplaneta americana, running at angles of 0, 45 and 90 degrees to the horizontal. Resting oxygen consumption (VO2rest) was not affected by incline angle. Steady-state oxygen consumption (VO2ss) increased linearly with speed at all angles of ascent. The minimum cost of locomotion (the slope of the VO2ss versus speed function) increased with increasing angle of ascent. The minimum cost of locomotion on 45 and 90 degrees inclines was two and three times greater, respectively, than the cost during horizontal running. The cockroach's metabolic cost of ascent greatly exceeds that predicted from the hypothesis of a constant efficiency for vertical work. Variations in stride frequency and contact time cannot account for the high metabolic cost, because they were independent of incline angle. An increase in the metabolic cost or amount of force production may best explain the increase in metabolic cost. Small animals, such as P. americana, can easily scale vertical surfaces, but the energetic cost is considerable.

Effect of variation in form on the cost of terrestrial locomotion

1990 ◽  
Vol 150 (1) ◽  
pp. 233-246 ◽  
Author(s):  
R. J. Full ◽  
D. A. Zuccarello ◽  
A. Tullis
Keyword(s):  
Oxygen Consumption ◽  
Body Mass ◽  
Minimum Cost ◽  
Metabolic Cost ◽  
Interspecific Variation ◽  
American Cockroach ◽  
Field Cricket ◽  
Terrestrial Locomotion ◽  
Cost Of Locomotion ◽  
The Cost

The mass-specific minimum cost of terrestrial locomotion (Cmin) decreases with an increase in body mass. This generalization spans nearly eight orders of magnitude in body mass and includes two phyla. The general relationship between metabolic cost and mass is striking. However, a significant amount of unexplained interspecific variation in Cmin exists at any given body mass. To determine how variation in morphology and physiology affects metabolic energy cost, we measured the oxygen consumption of three comparably sized insects running on a miniature treadmill; the American cockroach Periplaneta americana, the caterpillar hunting beetle Calosoma affine and the Australian field cricket Teleogryllus commodus. Steady-state oxygen consumption (VO2ss) increased linearly with speed. Cmin was similar for crickets and cockroaches (8.0 and 8.5 ml O2 g-1km-1, respectively), but was substantially lower for beetles (4.6 ml O2 g-1km-1). The predicted value of Cmin for all three insects was within the 95% confidence intervals of the Cmin versus body mass function. However, the 95% confidence intervals extend approximately 2.5-fold above and 40% below the regression line, making the variation at any given body mass nearly sixfold. Normalizing for the rate of muscle force production by determining the metabolic cost per stride failed to account for the interspecific variation in the cost of locomotion observed in the three insects. Ground contact costs (i.e. VO2ss multiplied by leg contact time during a stride) in insects were similar to those measured in mammals (1.5-3.1 J kg-1) and were independent of speed, but did not explain the interspecific variation in the cost of locomotion. Muscles of the caterpillar hunting beetle may have a greater mechanical advantage than muscles of the Australian field cricket and American cockroach. Variation in musculo-skeletal arrangement, apart from variation in body mass, could translate into significant differences in the minimum cost of terrestrial locomotion.

Speed, stride frequency and energy cost per stride: how do they change with body size and gait?

1988 ◽  
Vol 138 (1) ◽  
pp. 301-318 ◽  
Author(s):  
N. C. Heglund ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Energy Cost ◽  
Reaction Force ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Published Data ◽  
Frequency Change ◽  
Cost Of Locomotion ◽  
The Cost

In this study we investigate how speed and stride frequency change with body size. We use this information to define ‘equivalent speeds’ for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a gallop all change in the same rather dramatic manner with body size, differing by nine-fold between mice and horses (i.e. all three speeds scale with about the 0.2 power of body mass). Although the absolute speeds differ greatly, the maximum sustainable speed was about 2.6-fold greater than the minimum within a trot, and 2.1-fold greater within a gallop. The frequencies used to sustain the equivalent speeds (with the exception of the minimum trotting speed) scale with about the same factor, the −0.15 power of body mass. Combining this speed and frequency data with previously published data on the energetic cost of locomotion, we find that the mass-specific energetic cost of locomotion is almost directly proportional to the stride frequency used to sustain a constant speed at all the equivalent speeds within a trot and a gallop, except for the minimum trotting speed (where it changes by a factor of two over the size range of animals studied). Thus the energy cost per kilogram per stride at five of the six equivalent speeds is about the same for all animals, independent of body size, but increases with speed: 5.0 J kg-1 stride-1 at the preferred trotting speed; 5.3 J kg-1 stride-1 at the trot-gallop transition speed; 7.5 J kg-1 stride-1 at the preferred galloping speed; and 9.4 J kg-1 stride-1 at the maximum sustained galloping speed. The cost of locomotion is determined primarily by the cost of activating muscles and of generating a unit of force for a unit of time. Our data show that both these costs increase directly with the stride frequency used at equivalent speeds by different-sized animals. The increase in cost per stride with muscles (necessitating higher muscle forces for the same ground reaction force) as stride length increases both in the trot and in the gallop.

Moving cheaply: energetics of walking in the African elephant.

1995 ◽  
Vol 198 (3) ◽  
pp. 629-632 ◽  
Author(s):  
V A Langman ◽  
T J Roberts ◽  
J Black ◽  
G M Maloiy ◽  
N C Heglund ◽  
...  
Keyword(s):  
Fuel Economy ◽  
African Elephant ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Allometric Relationships ◽  
Cost Of Locomotion ◽  
Biological Laws ◽  
Large Animals ◽  
The Cost

Large animals have a much better fuel economy than small ones, both when they rest and when they run. At rest, each gram of tissue of the largest land animal, the African elephant, consumes metabolic energy at 1/20 the rate of a mouse; using existing allometric relationships, we calculate that it should be able to carry 1 g of its tissue (or a load) for 1 km at 1/40 the cost for a mouse. These relationships between energetics and size are so consistent that they have been characterized as biological laws. The elephant has massive legs and lumbers along awkwardly, suggesting that it might expend more energy to move about than other animals. We find, however, that its energetic cost of locomotion is predicted remarkably well by the allometric relationships and is the lowest recorded for any living land animal.

scholarly journals Energetic cost of locomotion as a function of ambient temperature and during growth in the marsupial Potorous tridactylus.

1993 ◽  
Vol 174 (1) ◽  
pp. 81-95
Author(s):  
R V Baudinette ◽  
E A Halpern ◽  
D S Hinds
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Multiple Regression ◽  
Stride Length ◽  
Energy Use ◽  
Linear Increase ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
Cost Of Locomotion

In the marsupial, the potoroo, multiple regression analysis shows that ambient temperature makes a minor (2%) contribution towards variation in oxygen consumption with speed. This suggests that the heat generated during running is substituted for heat which would otherwise have to be generated for temperature regulation. Maximum levels of oxygen consumption are also temperature-independent over the range 5-25 degrees C, but plasma lactate concentrations at the conclusion of exercise significantly increase with ambient temperature. Adult potoroos show a linear increase in oxygen consumption with speed, and multiple regression indicates that the most significant factor affecting energy use during running is stride length. Juvenile potoroos have an incremental cost of locomotion about 40% lower than that predicted on the basis of body mass. The smaller animals meet the demands of increasing speed by increasing stride length rather than stride frequency, as would be expected in a smaller species. Our results show that juvenile potoroos diverge significantly from models based only on adult animals in incremental changes in stride frequency, length and the cost of transport, suggesting that they are not simply scaled-down adults.

The work and energetic cost of locomotion. II. Partitioning the cost of internal and external work within a species

1990 ◽  
Vol 154 (1) ◽  
pp. 287-303 ◽  
Author(s):  
K. Steudel
Keyword(s):  
Center Of Mass ◽  
Elastic Strain Energy ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
External Work ◽  
Internal Work ◽  
Cost Of Locomotion ◽  
Large Animals ◽  
The Cost

Previous studies have shown that large animals have systematically lower mass-specific costs of locomotion than do smaller animals, in spite of there being no demonstrable difference between them in the mass-specific mechanical work of locomotion. Larger animals are somehow much more efficient at converting metabolic energy to mechanical work. The present study analyzes how this decoupling of work and cost might occur. The experimental design employs limb-loaded and back-loaded dogs and allows the energetic cost of locomotion to be partitioned between that used to move the center of mass (external work) and that used to move the limbs relative to the center of mass (internal work). These costs were measured in three dogs moving at four speeds. Increases in the cost of external work with speed parallel increases in the amount of external work based on data from previous studies. However, increases in the cost of internal work with speed are much less (less than 50%) than the increase in internal work itself over the speeds examined. Furthermore, the cost of internal work increases linearly with speed, whereas internal work itself increases as a power function of speed. It is suggested that this decoupling results from an increase with speed in the extent to which the internal work of locomotion is powered by non-metabolic means, such as elastic strain energy and transfer of energy within and between body segments.

scholarly journals Animal galloping and human hopping: an energetics and biomechanics laboratory exercise

2013 ◽  
Vol 37 (4) ◽  
pp. 377-383 ◽  
Author(s):  
Stan L. Lindstedt ◽  
Patrick M. Mineo ◽  
Paul J. Schaeffer
Keyword(s):  
Body Size ◽  
Metabolic Cost ◽  
Mechanical Efficiency ◽  
Lessons Learned ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Elastic Recoil ◽  
Laboratory Exercise ◽  
The Cost ◽  
Work Done

This laboratory exercise demonstrates fundamental principles of mammalian locomotion. It provides opportunities to interrogate aspects of locomotion from biomechanics to energetics to body size scaling. It has the added benefit of having results with robust signal to noise so that students will have success even if not “meticulous” in attention to detail. First, using respirometry, students measure the energetic cost of hopping at a “preferred” hop frequency. This is followed by hopping at an imposed frequency half of the preferred. By measuring the O2 uptake and work done with each hop, students calculate mechanical efficiency. Lessons learned from this laboratory include 1) that the metabolic cost per hop at half of the preferred frequency is nearly double the cost at the preferred frequency; 2) that when a person is forced to hop at half of their preferred frequency, the mechanical efficiency is nearly that predicted for muscle but is much higher at the preferred frequency; 3) that the preferred hop frequency is strongly body size dependent; and 4) that the hop frequency of a human is nearly identical to the galloping frequency predicted for a quadruped of our size. Together, these exercises demonstrate that humans store and recover elastic recoil potential energy when hopping but that energetic savings are highly frequency dependent. This stride frequency is dependent on body size such that frequency is likely chosen to maximize this function. Finally, by requiring students to make quantitative solutions using appropriate units and dimensions of the physical variables, these exercises sharpen analytic and quantitative skills.

Energetic Cost of Generating Muscular Force During Running: A Comparison of Large and Small Animals

1980 ◽  
Vol 86 (1) ◽  
pp. 9-18 ◽  
Author(s):  
C. RICHARD TAYLOR ◽  
NORMAN C. HEGLUND ◽  
THOMAS A. McMAHON ◽  
TODD R. LOONEY
Keyword(s):  
Oxygen Consumption ◽  
Energy Utilization ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Vertical Acceleration ◽  
Small Animals ◽  
Direct Proportion ◽  
Muscular Force ◽  
Contact Phase ◽  
Integral Number

The energetic cost of generating muscular force was studied by measuring the energetic cost of carrying loads in rats, dogs, humans, and horses for loads ranging between 7 and 27% of body mass. Oxygen consumption increased in direct proportion to mass supported by the muscles, i.e. V OO2,L/VOO2/mL/m = 1.01 ± S.D. ± 0.017, where VOO2,L is the oxygen consumption of the animal running with a load, VOO2 is the oxygen consumption at the same speed without a load, mL, is the mass of the animal plus the load, and m is the mass of the animal. Stride frequency, average number of feet on the ground over an integral number of strides, the time of contact of each foot relative to the other feet, and the average vertical acceleration during the contact phase were not measurably changed by the loads used in our experiments. From these observations we conclude that the average accelerations of the centre of mass of the animal are not changed by carrying the loads, and that muscular force developed by the animal increases in direct proportion to the load. It follows that the rate of energy utilization by muscles of an animal as it runs along the ground at any particular speed is nearly directly proportional to the force exerted by its muscles. The energetic cost of generating force over an interval of time (∫ F dt) increases markedly with running speed. An important consequence of the direct proportionality between increased oxygen consumption and mass of the load is that small animals expend much more energy to generate a given force at a given speed than large animals.

Energetic Cost of Running with different Muscle Temperatures in Savannah MOnitor Lizards

1982 ◽  
Vol 99 (1) ◽  
pp. 269-277
Author(s):  
LAWRENCE C. ROME
Keyword(s):  
Isometric Force ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Muscle Temperature ◽  
Apparent Difference ◽  
Muscle Energetics ◽  
Cost Of Locomotion ◽  
Monitor Lizards ◽  
The Cost

The purpose of this study was to determine whether the energetic cost of locomotion was independent of muscle temperature, or if it tripled with a 10 °C increase in temperature, like the cost of generating isometric force in isolated muscle preparations. For a given running speed of Savannah Monitor lizards, the energetic cost of locomotion (the difference between running and resting metabolism) was the same when muscle temperature was 28.5 °C as when it was 38 °C. It was also found that stride frequency and posture did not change with temperature, indicating that the average force exerted by the lizards' muscles during locomotion at the two temperatures was the same. This suggests that the cost of generating force in vivo is independent of temperature. Several possible explanations of the apparent difference between in vivo and in vitro muscle energetics are discussed.

scholarly journals Scaling of muscle fibres and locomotion

1992 ◽  
Vol 168 (1) ◽  
pp. 243-252 ◽  
Author(s):  
L. C. Rome
Keyword(s):  
Muscle Fibre ◽  
Body Mass ◽  
Fibre Type ◽  
Fibre Types ◽  
Energetic Cost ◽  
Muscle Fibres ◽  
Small Animals ◽  
Running Speed ◽  
Cost Of Locomotion ◽  
The Cost

To reconcile the scaling of the mechanics and energetics of locomotion to recent data on the scaling of the mechanics of muscle fibres, I have extended the theory of Taylor and colleagues that the energetic cost of locomotion is determined by the cost of generating force by the fibres. By assuming (1) that the cost of generating force in a fibre is proportional to V(max) (maximum velocity of shortening) and (2) that, at physiologically equivalent speeds, animals of different body sizes recruit the same fibre types, this extension quantitatively predicts the scaling of the energetics of locomotion, as well as other observations, from the scaling of V(max) of the muscle fibres. First, the energetic cost of locomotion at physiologically equivalent speeds scales with Mb-0.16, where Mb is body mass, as does V(max) of a given fibre type. However, the energetic cost at absolute speeds (cost of transport) scales with Mb-0.30, because small animals must compress their recruitment order into a narrower speed range and, hence, recruit faster muscle fibre types at a given running speed. Thus, it costs more for small animals to move 1 kg of their body mass 1 km not only because a given muscle fibre type from a small animal costs more to generate force than from a large one, but also because small animals recruit faster fibre types at a given absolute running speed. In addition, this analysis provides evidence that V(max) scales similarly to 1/tc (where tc is foot contact time) and muscle shortening velocity (V), in agreement with recent models. Finally, this extension predicts that, at physiologically equivalent speeds, the weight-specific energetic cost per step is independent of body size, as has been found empirically.

The Metabolic Cost of Swimming in Ducks

1970 ◽  
Vol 53 (3) ◽  
pp. 763-777 ◽  
Author(s):  
HENRY D. PRANGE ◽  
KNUT SCHMIDT-NIELSEN
Keyword(s):  
Oxygen Consumption ◽  
Swimming Speed ◽  
Swimming Performance ◽  
Water Channel ◽  
Minimum Cost ◽  
Metabolic Cost ◽  
Power Input ◽  
Cost Of Transport ◽  
Overall Efficiency ◽  
The Cost

1. The metabolic cost of swimming was studied in mallard ducks (Anas platyrhynchos) which had been trained to swim steadily in a variable-speed water channel. 2. At speeds of from 0.35 to 0.50 m/sec the oxygen consumption remained relatively constant at approximately 2.2 times the resting level. At speeds of 0.55 m/sec and higher the oxygen consumption increased rapidly and reached 4.1 times resting at the maximum sustainable speed of 0.70 m/sec. 3. The maximum sustainable swimming speed of the ducks coincided with the limit predicted from hydrodynamic considerations of the water resistance of a displacement-hulled ship of the same hull length as a duck (0.33 m). 4. The cost of transport (metabolic rate/speed) reached a minimum of 5.77 kcal/kg km at a swimming speed of 0.50 m/sec. Ducks swimming freely on a pond were observed to swim at the speed calculated in experimental trials to give minimum cost of transport. 5. Drag measurements made with model ducks indicated a maximum overall efficiency (power output/power input) for the swimming ducks of about 5%. Ships typically have maximum efficiencies of 20-30%. Because of the difficulty in delimiting the cost of swimming activity alone from the other bodily functions of the duck, overall efficiency may present an incorrect description of the swimming performance of the duck relative to that of a ship. An hydrodynamic parameter such as speed/length ratio [speed/(hull length)½] whereby a duck excels conventional ships may present a more appropriate comparison.

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