Inexpensive load carrying by rhinoceros beetles

1996 ◽  
Vol 199 (3) ◽  
pp. 609-612 ◽  
Author(s):  
R Kram
Keyword(s):  
Body Mass ◽  
Metabolic Cost ◽  
Added Mass ◽  
Metabolic Energy ◽  
Direct Proportion ◽  
Total Load ◽  
Load Carrying ◽  
Cost Of Locomotion ◽  
Conventional Models ◽  
Energy Cost Of Locomotion

These experiments determined the magnitude of loads that rhinoceros beetles (Scarabaeidae) can carry and also the metabolic energy required for carrying loads. I hypothesized that, like many other animals, these beetles would have metabolic rates in direct proportion to the total load (body mass plus added mass). Eight beetles (Xylorctes thestalus) walked at 1 cm s-1 on a motorized treadmill enclosed in a respirometer. The beetles could sustain this speed with loads of more than 30 times their body mass. In addition to being strong, these beetles carry loads with remarkable economy. The metabolic cost of moving a gram of additional load was more than five times cheaper than that of moving a gram of body mass. This phenomenon cannot be explained by conventional models that link the biomechanics and metabolic energy cost of locomotion.

THE ENERGETIC COSTS OF CALLING IN THE BUSHCRICKET REQUENA VERTICALIS (ORTHOPTERA: TETTIGONIIDAE: LISTROSCELIDINAE)

1993 ◽  
Vol 178 (1) ◽  
pp. 21-37 ◽  
Author(s):  
W. J. Bailey ◽  
P. C. Withers ◽  
M. Endersby ◽  
K. Gaull
Keyword(s):  
Body Mass ◽  
Sound Pressure ◽  
Metabolic Cost ◽  
Acoustic Power ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Metabolic Efficiency ◽  
Metabolic Costs ◽  
Sound Pressure Levels ◽  
The Relationship

1. The metabolic costs of calling for male Requena verticalis Walker (Tettigoniidae: Listroscelidinae) were measured by direct recordings of oxygen consumption. The acoustic power output was measured by sound pressure levels around the calling bushcricket. 2. The average metabolic cost of calling was 0.143 ml g-1 h-1 but depended on calling rate. The net metabolic cost of calling per unit call, the syllable, was calculated to be 4.34×10-6+/−8.3×10-7 ml O2 syllable-1 g-1 body mass (s.e.) from the slope of the relationship between total V(dot)O2 and rate of syllable production. The resting V(dot)O2, calculated as the intercept of the relationship, was 0.248 ml O2 g-1 body mass h-1. 3. The energetic cost of calling for R. verticalis (average mass 0.37 g) was estimated at 31.85×10-6 J syllable-1. 4. Sound pressure levels were measured around calling insects. The surface area of a sphere of uniform sound pressure level [83 dB SPL root mean square (RMS) acoustic power] obtained by these measurements was used to calculate acoustic power. This was 0.20 mW. 5. The metabolic efficiency of calling, based on total metabolic energy utilisation, was 6.4 %. However, we propose that the mechanical efficiency for acoustic transmission is closer to 57 %, since only about 10 % of muscle metabolic energy is apparently available for sound production. 6. R. verticalis emits chirps formed of several syllables within which are discrete sound pulses. Wing stroke rates, when the insect is calling at its maximal rate, were approximately 583 min-1. This is slow compared to the rates observed in conehead tettigoniids, the only other group of bushcrickets where metabolic costs have been measured. The thoracic temperatures of males that had been calling for 5 min were not significantly different from those of non-calling males. 7. For R. verticalis, calling with relatively slow syllable rates may reduce the total cost of calling, and this may be a compensatory mechanism for their other high energetic cost of mating (a large spermatophylax).

Energetic cost of locomotion in the tammar wallaby

1992 ◽  
Vol 262 (5) ◽  
pp. R771-R778 ◽  
Author(s):  
R. V. Baudinette ◽  
G. K. Snyder ◽  
P. B. Frappell
Keyword(s):  
Oxygen Consumption ◽  
Blood Lactate ◽  
Body Mass ◽  
Energy Cost ◽  
Physiological Adaptation ◽  
Energetic Cost ◽  
Cost Of Locomotion ◽  
Lactate Levels ◽  
Energy Cost Of Locomotion ◽  
Blood Lactate Levels

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.

scholarly journals Metabolic cost of generating muscular force in human walking: insights from load-carrying and speed experiments

2003 ◽  
Vol 95 (1) ◽  
pp. 172-183 ◽  
Author(s):  
Timothy M. Griffin ◽  
Thomas J. Roberts ◽  
Rodger Kram
Keyword(s):  
Metabolic Rate ◽  
Stance Phase ◽  
Metabolic Cost ◽  
Direct Proportion ◽  
Muscular Force ◽  
Active Muscle ◽  
Cost Coefficient ◽  
Load Carrying ◽  
Leg Muscle ◽  
The Cost

We sought to understand how leg muscle function determines the metabolic cost of walking. We first indirectly assessed the metabolic cost of swinging the legs and then examined the cost of generating muscular force during the stance phase. Four men and four women walked at 0.5, 1.0, 1.5, and 2.0 m/s carrying loads equal to 0, 10, 20, and 30% body mass positioned symmetrically about the waist. The net metabolic rate increased in nearly direct proportion to the external mechanical power during moderate-speed (0.5–1.5 m/s) load carrying, suggesting that the cost of swinging the legs is relatively small. The active muscle volume required to generate force on the ground and the rate of generating this force accounted for >85% of the increase in net metabolic rate across moderate speeds and most loading conditions. Although these factors explained less of the increase in metabolic rate between 1.5 and 2.0 m/s (∼50%), the cost of generating force per unit volume of active muscle [i.e., the cost coefficient ( k)] was similar across all conditions [ k = 0.11 ± 0.03 (SD) J/cm3]. These data indicate that, regardless of the work muscles do, the metabolic cost of walking can be largely explained by the cost of generating muscular force during the stance phase.

Carrying Loads. The Cost of Generating Muscular Force

Physiology ◽  
1986 ◽  
Vol 1 (5) ◽  
pp. 153-155
Author(s):  
CR Taylor
Keyword(s):  
Body Mass ◽  
Metabolic Cost ◽  
African Women ◽  
Muscular Force ◽  
Load Carrying ◽  
The Cost

African women can carry loads of 20% of their body mass on their heads without measurable metabolic cost. In contrast, trained or untrained humans and animals increase their metabolism by 20% when they carry loads of this magnitude. Two possible mechanisms are proposed for the women's economic means of load carrying, based on considerations of the cost of generating muscular force during locomotion.

Independent metabolic costs of supporting body weight and accelerating body mass during walking

2005 ◽  
Vol 98 (2) ◽  
pp. 579-583 ◽  
Author(s):  
Alena Grabowski ◽  
Claire T. Farley ◽  
Rodger Kram
Keyword(s):  
Body Weight ◽  
Metabolic Rate ◽  
Body Mass ◽  
Center Of Mass ◽  
Metabolic Cost ◽  
Added Mass ◽  
Normal Walking ◽  
Reduced Gravity ◽  
The Cost ◽  
Support Body Weight

The metabolic cost of walking is determined by many mechanical tasks, but the individual contribution of each task remains unclear. We hypothesized that the force generated to support body weight and the work performed to redirect and accelerate body mass each individually incur a significant metabolic cost during normal walking. To test our hypothesis, we measured changes in metabolic rate in response to combinations of simulated reduced gravity and added loading. We found that reducing body weight by simulating reduced gravity modestly decreased net metabolic rate. By calculating the metabolic cost per Newton of reduced body weight, we deduced that generating force to support body weight comprises ∼28% of the metabolic cost of normal walking. Similar to previous loading studies, we found that adding both weight and mass increased net metabolic rate in more than direct proportion to load. However, when we added mass alone by using a combination of simulated reduced gravity and added load, net metabolic rate increased about one-half as much as when we added both weight and mass. By calculating the cost per kilogram of added mass, we deduced that the work performed on the center of mass comprises ∼45% of the metabolic cost of normal walking. Our findings support the hypothesis that force and work each incur a significant metabolic cost. Specifically, the cost of performing work to redirect and accelerate the center of mass is almost twice as great as the cost of generating force to support body weight.

scholarly journals Energy demand during exponential growth of Octopus maya: exploring the effect of age and weight

2010 ◽  
Vol 67 (7) ◽  
pp. 1501-1508 ◽  
Author(s):  
Felipe Briceño ◽  
Maite Mascaró ◽  
Carlos Rosas
Keyword(s):  
Food Intake ◽  
Body Mass ◽  
Respiration Rate ◽  
Exponential Growth ◽  
Mass Production ◽  
Energy Demand ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Octopus Maya ◽  
Effect Of Age

Abstract Briceño, F., Mascaró, M., and Rosas, C. 2010. Energy demand during exponential growth of Octopus maya: exploring the effect of age and weight. – ICES Journal of Marine Science, 67: 1501–1508. Recent work has reported changes associated with physiological, morphological, and behavioural adaptation during the absorption of yolk reserves. The holobenthic endemic species Octopus maya was used to explore the energy supply needed from the food intake (I; J animal−1 d−1) to supply the rate of production energy needed for body mass (P; J animal−1 d−1) and respiration rate (R; J animal−1 d−1) as a function of weight and age during the exponential early growth phase of the animal. Individually housed juveniles from hatching (1 d) to 105 d after hatching (DAH) were used, with the age and weight known, and the relationship between oxygen consumption (VO2; mg O2 animal−1 d−1) and weight (g) was established. Projections of I, R, and P as a function of age (Z) were made. The food intake destined to supply body mass production (%P/I) and respiration rate energy (%R/I) was analysed for an extended age range of 1–150 DAH. When O. maya juveniles hatched, they had a greater requirement for R than for P from the food intake, 61% (%R/I) and 13% (%P/I), respectively, suggesting high metabolic cost associated with post-hatching (during yolk absorption). Within the period where ZR > ZP (1–105 DAH), there was sufficient metabolic energy to satisfy the demands for sustaining exponential body mass production. The age at which %R/I = %P/I delimits the point where P cannot increase for reasons of metabolic constraint.

scholarly journals A PHYSIOLOGIST'S PERSPECTIVE ON ROBOTIC EXOSKELETONS FOR HUMAN LOCOMOTION

2007 ◽  
Vol 04 (03) ◽  
pp. 507-528 ◽  
Author(s):  
DANIEL P. FERRIS ◽  
GREGORY S. SAWICKI ◽  
MONICA A. DALEY
Keyword(s):  
Science Fiction ◽  
Metabolic Cost ◽  
Human Locomotion ◽  
Metabolic Energy ◽  
Future Research ◽  
Future Studies ◽  
Technological Advances ◽  
Cost Of Locomotion ◽  
Metabolic Energy Expenditure ◽  
Insight Into

Technological advances in robotic hardware and software have enabled powered exoskeletons to move from science fiction to the real world. The objective of this article is to emphasize two main points for future research. First, the design of future devices could be improved by exploiting biomechanical principles of animal locomotion. Two goals in exoskeleton research could particularly benefit from additional physiological perspective: (i) reduction in the metabolic energy expenditure of the user while wearing the device, and (ii) minimization of the power requirements for actuating the exoskeleton. Second, a reciprocal potential exists for robotic exoskeletons to advance our understanding of human locomotor physiology. Experimental data from humans walking and running with robotic exoskeletons could provide important insight into the metabolic cost of locomotion that is impossible to gain with other methods. Given the mutual benefits of collaboration, it is imperative that engineers and physiologists work together in future studies on robotic exoskeletons for human locomotion.

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.

Energetics of bipedal running. I. Metabolic cost of generating force.

1998 ◽  
Vol 201 (19) ◽  
pp. 2745-2751 ◽  
Author(s):  
T J Roberts ◽  
R Kram ◽  
P G Weyand ◽  
C R Taylor
Keyword(s):  
Body Weight ◽  
Energy Consumption ◽  
Metabolic Rate ◽  
Body Mass ◽  
Energy Use ◽  
Force Production ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Force Generation ◽  
Running Mechanics

Similarly sized bipeds and quadrupeds use nearly the same amount of metabolic energy to run, despite dramatic differences in morphology and running mechanics. It has been shown that the rate of metabolic energy use in quadrupedal runners and bipedal hoppers can be predicted from just body weight and the time available to generate force as indicated by the duration of foot-ground contact. We tested whether this link between running mechanics and energetics also applies to running bipeds. We measured rates of energy consumption and times of foot contact for humans (mean body mass 78.88 kg) and five species of birds (mean body mass range 0.13-40.1 kg). We find that most (70-90%) of the increase in metabolic rate with speed in running bipeds can be explained by changes in the time available to generate force. The rate of force generation also explains differences in metabolic rate over the size range of birds measured. However, for a given rate of force generation, birds use on average 1.7 times more metabolic energy than quadrupeds. The rate of energy consumption for a given rate of force generation for humans is intermediate between that of birds and quadrupeds. These results support the idea that the cost of muscular force production determines the energy cost of running and suggest that bipedal runners use more energy for a given rate of force production because they require a greater volume of muscle to support their body weight.

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