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.

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.

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.

scholarly journals The rising cost of warming waters: effects of temperature on the cost of swimming in fishes

2011 ◽  
Vol 8 (2) ◽  
pp. 266-269 ◽  
Author(s):  
Andrew M. Hein ◽  
Katrina J. Keirsted
Keyword(s):  
Water Temperature ◽  
Fish Species ◽  
Global Climate ◽  
Swimming Performance ◽  
Metabolic Cost ◽  
Quantitative Model ◽  
The Body ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
The Cost

Understanding the effects of water temperature on the swimming performance of fishes is central in understanding how fish species will respond to global climate change. Metabolic cost of transport (COT)—a measure of the energy required to swim a given distance—is a key performance parameter linked to many aspects of fish life history. We develop a quantitative model to predict the effect of water temperature on COT. The model facilitates comparisons among species that differ in body size by incorporating the body mass-dependence of COT. Data from 22 fish species support the temperature and mass dependencies of COT predicted by our model, and demonstrate that modest differences in water temperature can result in substantial differences in the energetic cost of swimming.

scholarly journals Running Stride Length And Rate Are Changed And Mechanical Efficiency Is Preserved After Cycling In Middle-Level Triathletes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rodrigo Gomes da Rosa ◽  
Henrique Bianchi de Oliveira ◽  
Luca Paolo Ardigò ◽  
Natalia Andrea Gomeñuka ◽  
Gabriela Fischer ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Stride Length ◽  
Metabolic Cost ◽  
Mechanical Efficiency ◽  
Middle Level ◽  
Moderate Intensity ◽  
Cost Of Transport ◽  
Spatiotemporal Parameters ◽  
The Cost

AbstractAlthough cycling impairs the subsequent metabolic cost and performance of running in some triathletes, the consequences on mechanical efficiency (Eff) and kinetic and potential energy fluctuations of the body center of mass are still unknown. The aim of this study was to investigate the effects of previous cycling on the cost-of-transport, Eff, mechanical energy fluctuations (Wtot), spring stiffness (Kleg and Kvert) and spatiotemporal parameters. Fourteen middle-level triathletes (mean ± SD: maximal oxygen uptake, $$\dot{{\rm{V}}}$$V̇O2max = 65.3 ± 2.7 ml.kg−1.min−1, age = 30 ± 5 years, practice time = 6.8 ± 3.0 years) performed four tests. Two maximal oxygen uptake tests on a cycle ergometer and treadmill, and two submaximal 20-minute running tests (14 km.h−1) with (prior-cycling) and without (control) a previous submaximal 30-minute cycling test. No differences were observed between the control and post-cycling groups in Eff or Wtot. The Eff remains unchanged between conditions. On the other hand, the Kvert (20.2 vs 24.4 kN.m−1) and Kleg (7.1 vs 8.2 kN.m−1, p < 0.05) were lower and the cost-of-transport was higher (p = 0.018, 3.71 vs 3.31 J.kg−1.m−1) when running was preceded by cycling. Significantly higher stride frequency (p < 0.05, 1.46 vs 1.43 Hz) and lower stride length (p < 0.05, 2.60 vs 2.65 m) were observed in the running after cycling condition in comparison with control condition. Mechanical adjustments were needed to maintain the Eff, even resulting in an impaired metabolic cost after cycling performed at moderate intensity. These findings are compatible with the concept that specific adjustments in spatiotemporal parameters preserve the Eff when running is preceded by cycling in middle-level triathletes, though the cost-of-transport increased.

Negligible energetic cost of sonar jamming in a bat–moth interaction

2015 ◽  
Vol 93 (4) ◽  
pp. 331-335
Author(s):  
A.J. Corcoran ◽  
H.A. Woods
Keyword(s):  
Sound Production ◽  
Resting Metabolic Rate ◽  
Metabolic Cost ◽  
Energetic Cost ◽  
Metabolic Power ◽  
Model Species ◽  
Predator Prey ◽  
Acoustic Signaling ◽  
The Subject ◽  
The Cost

Energetic cost can constrain how frequently animals exhibit behaviors. The energetic cost of acoustic signaling for communication has been the subject of numerous studies; however, the cost of acoustic signaling for predator defense has not been addressed. We studied the energetic cost and efficiency of sound production for the clicks produced by the moth Bertholdia trigona (Grote, 1879) (Grote’s bertholdia) to jam the sonar of predatory bats. This moth is an excellent model species because of its extraordinary ability to produce sound—it clicks at the highest known rate of any moth, up to 4500 clicks·s–1. We measured the metabolic cost of clicking, resting, and flying from moths suspended in a respirometry chamber. Clicking was provoked by playing back an echolocation attack sequence. The cost of sound production for B. trigona was low (66% of resting metabolic rate) and the acoustic efficiency, or the percentage of metabolic power that is converted into sound, was moderately high (0.30% ± 0.15%) compared with other species. We discuss mechanisms that allow B. trigona to achieve their extraordinary clicking rates and high acoustic efficiency. Clicking for jamming bat sonar incurs negligible energetic cost to moths despite being the most effective known anti-bat defense. These results have implications for both the ecology of predator–prey interactions and the evolution of jamming signals.

scholarly journals Mechanical Work Accounts for Most of the Energetic Cost in Human Running

2020 ◽  
Author(s):  
RC Riddick ◽  
AD Kuo
Keyword(s):  
Lower Cost ◽  
Metabolic Cost ◽  
Energetic Cost ◽  
Active Muscle ◽  
Muscle Work ◽  
Direct Measurements ◽  
The Cost ◽  
Tissue Deformations ◽  
Human Running ◽  
Series Elastic

AbstractThe metabolic cost of human running is challenging to explain, in part because direct measurements of muscles are limited in availability. Active muscle work costs substantial energy, but series elastic tissues such as tendon may also perform work while muscles contract isometrically at a lower cost. While it is unclear to what extent muscle vs. series elastic work occurs, there are indirect data that can help resolve their relative contributions to the cost of running. We therefore developed a simple cost estimate for muscle work in humans running (N = 8) at moderate speeds based on measured joint energetics. We found that even if 50% of the work observed at the joints is performed passively, active muscle work still accounts for 76% of the net energetic cost. Up to 24% of this cost due is required to compensate for dissipation from soft tissue deformations. The cost of active work may be further adjusted based on assumptions of multi-articular energy transfer and passive elasticity, but even the most conservative assumptions yield active work costs of at least 60%. Passive elasticity can greatly reduce the active work of running, but muscle work still explains most of the overall energetic cost.

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.

LIFE SKILLS EDUCATION FOR SCHOOL DROP OUTS IN TAMAN SARI, DISTRICT BOGOR REGENCY

2019 ◽  
Vol 1 (2) ◽  
pp. 46
Author(s):  
Stefani Nawati EKORESTI
Keyword(s):  
Life Skills ◽  
Economic Value ◽  
Skills Training ◽  
Poor People ◽  
Housing Conditions ◽  
The Cost ◽  
Skills Education ◽  
Work Done ◽  
Drop Outs ◽  
Life Skills Education

Taman Sari Sub-District, Bogor Regency has the potential for fertile soil. But these lands have not been tilled properly. Narrow housing conditions, especially for poor people, do not allow residents to plant crops. Causing the lack of consumption of vegetables; which causes residents become easily sick. In addition, there is also a lot of plastic waste, especially bottled drinking water and other things that come from tourists and fishermen who have not been processed. This condition gave rise to the idea to provide life skills training in making vertical gardens, hydroponic plants and waste management. Besides the need for makeup and haircutting skills also needed especially for orphans fostered by Yasayan Usawatun Hasanah. Community Service Activities (PkM) aims to foster community awareness of the cleanliness of the environment and empower citizens to be more creative and entrepreneurial. Therefore, in addition to the types of activities requested by the residents, UPBJJ-UT Bogor will also teach about identifying the economic value of the work done in the form of determining the cost of goods sold / production. This activity was attended by 50 orphans and it ran smoothly and successfully. Now orphans already have life skills that hope can lift their economy.

scholarly journals Amelioration of the Cost of Conjugative Plasmid Carriage in Eschericha coli K12

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 1641-1649
Author(s):  
Cecilia Dahlberg ◽  
Lin Chao
Keyword(s):  
Drug Resistance ◽  
Multiple Drug Resistance ◽  
Conjugative Plasmid ◽  
Energetic Cost ◽  
Multiple Drug ◽  
Genetic Changes ◽  
Batch Cultures ◽  
Transfer Rates ◽  
Bacterial Plasmid ◽  
The Cost

Abstract Although plasmids can provide beneficial functions to their host bacteria, they might confer a physiological or energetic cost. This study examines how natural selection may reduce the cost of carrying conjugative plasmids with drug-resistance markers in the absence of antibiotic selection. We studied two plasmids, R1 and RP4, both of which carry multiple drug resistance genes and were shown to impose an initial fitness cost on Escherichia coli. To determine if and how the cost could be reduced, we subjected plasmid-containing bacteria to 1100 generations of evolution in batch cultures. Analysis of the evolved populations revealed that plasmid loss never occurred, but that the cost was reduced through genetic changes in both the plasmids and the bacteria. Changes in the plasmids were inferred by the demonstration that evolved plasmids no longer imposed a cost on their hosts when transferred to a plasmid-free clone of the ancestral E. coli. Changes in the bacteria were shown by the lowered cost when the ancestral plasmids were introduced into evolved bacteria that had been cured of their (evolved) plasmids. Additionally, changes in the bacteria were inferred because conjugative transfer rates of evolved R1 plasmids were lower in the evolved host than in the ancestral host. Our results suggest that once a conjugative bacterial plasmid has invaded a bacterial population it will remain even if the original selection is discontinued.

scholarly journals Energy cost and muscular activity required for propulsion during walking

2003 ◽  
Vol 94 (5) ◽  
pp. 1766-1772 ◽  
Author(s):  
Jinger S. Gottschall ◽  
Rodger Kram
Keyword(s):  
Body Weight ◽  
Muscular Activity ◽  
Metabolic Cost ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Horizontal Force ◽  
Normal Walking ◽  
The Mean ◽  
The Cost ◽  
Muscle Actions

We reasoned that with an optimal aiding horizontal force, the reduction in metabolic rate would reflect the cost of generating propulsive forces during normal walking. Furthermore, the reductions in ankle extensor electromyographic (EMG) activity would indicate the propulsive muscle actions. We applied horizontal forces at the waist, ranging from 15% body weight aiding to 15% body weight impeding, while subjects walked at 1.25 m/s. With an aiding horizontal force of 10% body weight, 1) the net metabolic cost of walking decreased to a minimum of 53% of normal walking, 2) the mean EMG of the medial gastrocnemius (MG) during the propulsive phase decreased to 59% of the normal walking magnitude, and yet 3) the mean EMG of the soleus (Sol) did not decrease significantly. Our data indicate that generating horizontal propulsive forces constitutes nearly half of the metabolic cost of normal walking. Additionally, it appears that the MG plays an important role in forward propulsion, whereas the Sol does not.

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