scholarly journals Kinematics of males Eupalaestrus weijenberghi (Araneae, Theraphosidae) locomotion on different substrates and inclines

2019 ◽  
Author(s):  
Valentina Silva-Pereyra ◽  
C Gabriel Fábrica ◽  
Carlo M Biancardi ◽  
Fernando Pérez-Miles
Keyword(s):  
Energy Saving ◽  
The Body ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Time Lags ◽  
Gait Patterns ◽  
Unit Distance ◽  
Body Segments ◽  
Gait Parameters

Background: For males of several terrestrial spiders the reproductive success depends to their locomotors performances. However, their mechanics of locomotion has been scarcely investigated. Aim of this work was to describe the gait patterns, analyse the gait parameters, the mechanics of locomotion and the energy saving mechanisms of Eupalaestrus weijenberghi (Araneae, Theraphosidae) on different inclinations and surfaces. Methods: Tarantulas were collected and marked for kinematic analysis. Free displacements, both at level and on incline, were recorded using two different experimental surfaces: glass and Teflon. Body segments of the experimental animals have been measured, weighted and their centre of mass experimentally determined. Through the reconstruction of trajectories of the body segments, we estimate the mechanical internal and external works and analysed the gait patterns. Results: Four gait patterns have been described, but spiders mainly employed a walk-trot-like gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected among different planes or surfaces in duty factor, time lags, stride frequency and stride length. However, postural changes were observed on slippery surfaces. The mechanical work at level was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all the total mechanical work. The internal work was extremely low, and did not increase with gradient. Discussion: Our results support the idea of the two quadrupeds in series: the anterior composed by the first two pairs of limbs, with more explorative and steering purpose, and the posterior more involved in supporting the body weight. The mechanical work to move one unit mass a unit distance is almost constant among the different species. However spiders show lower values than expected. Minimizing the mechanical work could help to limit the metabolic energy expenditure that, in small animals, is relatively very high. However, the energy recovery due to the inverted pendulum mechanics only account for a small part of energy saving. Adhesive setae present in the tarsal, scopulae and claw tufts, would participate in different ways during different moments of the step cycle, compensating part of the energetic cost on gradient, and helping to maintain constant the gait parameters.

scholarly journals Kinematics of males Eupalaestrus weijenberghi (Araneae, Theraphosidae) locomotion on different substrates and inclines

2019 ◽  
Author(s):  
Valentina Silva-Pereyra ◽  
C Gabriel Fábrica ◽  
Carlo M Biancardi ◽  
Fernando Pérez-Miles
Keyword(s):  
Energy Saving ◽  
The Body ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Time Lags ◽  
Gait Patterns ◽  
Unit Distance ◽  
Body Segments ◽  
Gait Parameters

Background: For males of several terrestrial spiders the reproductive success depends to their locomotors performances. However, their mechanics of locomotion has been scarcely investigated. Aim of this work was to describe the gait patterns, analyse the gait parameters, the mechanics of locomotion and the energy saving mechanisms of Eupalaestrus weijenberghi (Araneae, Theraphosidae) on different inclinations and surfaces. Methods: Tarantulas were collected and marked for kinematic analysis. Free displacements, both at level and on incline, were recorded using two different experimental surfaces: glass and Teflon. Body segments of the experimental animals have been measured, weighted and their centre of mass experimentally determined. Through the reconstruction of trajectories of the body segments, we estimate the mechanical internal and external works and analysed the gait patterns. Results: Four gait patterns have been described, but spiders mainly employed a walk-trot-like gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected among different planes or surfaces in duty factor, time lags, stride frequency and stride length. However, postural changes were observed on slippery surfaces. The mechanical work at level was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all the total mechanical work. The internal work was extremely low, and did not increase with gradient. Discussion: Our results support the idea of the two quadrupeds in series: the anterior composed by the first two pairs of limbs, with more explorative and steering purpose, and the posterior more involved in supporting the body weight. The mechanical work to move one unit mass a unit distance is almost constant among the different species. However spiders show lower values than expected. Minimizing the mechanical work could help to limit the metabolic energy expenditure that, in small animals, is relatively very high. However, the energy recovery due to the inverted pendulum mechanics only account for a small part of energy saving. Adhesive setae present in the tarsal, scopulae and claw tufts, would participate in different ways during different moments of the step cycle, compensating part of the energetic cost on gradient, and helping to maintain constant the gait parameters.

scholarly journals Kinematics of male Eupalaestrus weijenberghi (Araneae, Theraphosidae) locomotion on different substrates and inclines

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7748 ◽  
Author(s):  
Valentina Silva-Pereyra ◽  
C Gabriel Fábrica ◽  
Carlo M. Biancardi ◽  
Fernando Pérez-Miles
Keyword(s):  
The Body ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Time Lags ◽  
External Work ◽  
Gait Patterns ◽  
Unit Distance ◽  
Body Segments ◽  
Gait Parameters

Background The mechanics and energetics of spider locomotion have not been deeply investigated, despite their importance in the life of a spider. For example, the reproductive success of males of several species is dependent upon their ability to move from one area to another. The aim of this work was to describe gait patterns and analyze the gait parameters of Eupalaestrus weijenberghi (Araneae, Theraphosidae) in order to investigate the mechanics of their locomotion and the mechanisms by which they conserve energy while traversing different inclinations and surfaces. Methods Tarantulas were collected and marked for kinematic analysis. Free displacements, both level and on an incline, were recorded using glass and Teflon as experimental surfaces. Body segments of the experimental animals were measured, weighed, and their center of mass was experimentally determined. Through reconstruction of the trajectories of the body segments, we were able to estimate their internal and external mechanical work and analyze their gait patterns. Results Spiders mainly employed a walk-trot gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected regarding the different planes or surfaces with respect to duty factor, time lags, stride frequency, and stride length. However, postural changes were observed on slippery surfaces. The mechanical work required for traversing a level plane was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all of the total mechanical work. The internal work was extremely low and did not rise as the gradient increased. Discussion Our results support the idea of considering the eight limbs functionally divided into two quadrupeds in series. The anterior was composed of the first two pairs of limbs, which have an explorative and steering purpose and the posterior was more involved in supporting the weight of the body. The mechanical work to move one unit of mass a unit distance is almost constant among the different species tested. However, spiders showed lower values than expected. Minimizing the mechanical work could help to limit metabolic energy expenditure that, in small animals, is relatively very high. However, energy recovery due to inverted pendulum mechanics only accounts for only a small fraction of the energy saved. Adhesive setae present in the tarsal, scopulae, and claw tufts could contribute in different ways during different moments of the step cycle, compensating for part of the energetic cost on gradients which could also help to maintain constant gait parameters.

scholarly journals Elastic energy savings and active energy cost in a simple model of running

2021 ◽  
Vol 17 (11) ◽  
pp. e1009608
Author(s):  
Ryan T. Schroeder ◽  
Arthur D. Kuo
Keyword(s):  
Elastic Energy ◽  
Energy Cost ◽  
Energy Savings ◽  
Mechanical Energy ◽  
Metabolic Cost ◽  
The Body ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Mass Model ◽  
Human Running

The energetic economy of running benefits from tendon and other tissues that store and return elastic energy, thus saving muscles from costly mechanical work. The classic “Spring-mass” computational model successfully explains the forces, displacements and mechanical power of running, as the outcome of dynamical interactions between the body center of mass and a purely elastic spring for the leg. However, the Spring-mass model does not include active muscles and cannot explain the metabolic energy cost of running, whether on level ground or on a slope. Here we add explicit actuation and dissipation to the Spring-mass model, and show how they explain substantial active (and thus costly) work during human running, and much of the associated energetic cost. Dissipation is modeled as modest energy losses (5% of total mechanical energy for running at 3 m s-1) from hysteresis and foot-ground collisions, that must be restored by active work each step. Even with substantial elastic energy return (59% of positive work, comparable to empirical observations), the active work could account for most of the metabolic cost of human running (about 68%, assuming human-like muscle efficiency). We also introduce a previously unappreciated energetic cost for rapid production of force, that helps explain the relatively smooth ground reaction forces of running, and why muscles might also actively perform negative work. With both work and rapid force costs, the model reproduces the energetics of human running at a range of speeds on level ground and on slopes. Although elastic return is key to energy savings, there are still losses that require restorative muscle work, which can cost substantial energy during running.

Efficiency of uphill locomotion in nocturnal and diurnal lizards

1996 ◽  
Vol 199 (3) ◽  
pp. 587-592 ◽  
Author(s):  
C Farley ◽  
M Emshwiller
Keyword(s):  
Body Mass ◽  
Low Cost ◽  
Minimum Cost ◽  
Mechanical Work ◽  
Energetic Cost ◽  
Cost Of Transport ◽  
Unit Distance ◽  
Cost Of Locomotion ◽  
Average Body Mass ◽  
Average Body

Nocturnal geckos can walk on level ground more economically than diurnal lizards. One hypothesis for why nocturnal geckos have a low cost of locomotion is that they can perform mechanical work during locomotion more efficiently than other lizards. To test this hypothesis, we compared the efficiency of the nocturnal gecko Coleonyx variegatus (average body mass 4.2 g) and the diurnal skink Eumeces skiltonianus (average body mass 4.8 g) when they performed vertical work during uphill locomotion. We measured the rate of oxygen consumption when each species walked on the level and up a 50 slope over a range of speeds. For Coleonyx variegatus, the energetic cost of traveling a unit distance (the minimum cost of transport, Cmin) increased from 1.5 to 2.7 ml O2 kg-1 m-1 between level and uphill locomotion. For Eumeces skiltonianus, Cmin increased from 2.5 to 4.7 ml O2 kg-1 m-1 between level and uphill locomotion. By taking the difference between Cmin for level and uphill locomotion, we found that the efficiency of performing vertical work during locomotion was 37 % for Coleonyx variegatus and 19 % for Eumeces skiltonianus. The similarity between the 1.9-fold difference in vertical efficiency and the 1.7-fold difference in the cost of transport on level ground is consistent with the hypothesis that nocturnal geckos have a lower cost of locomotion than other lizards because they can perform mechanical work during locomotion more efficiently.

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.

Does the application of ground force set the energetic cost of cross-country skiing?

1998 ◽  
Vol 85 (5) ◽  
pp. 1736-1743 ◽  
Author(s):  
Matthew J. Bellizzi ◽  
Kellin A. D. King ◽  
Sara K. Cushman ◽  
Peter G. Weyand
Keyword(s):  
Time Course ◽  
Weight Bearing ◽  
The Body ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Metabolic Rates ◽  
Force Application ◽  
Stride Rate ◽  
Cross Country Skiing ◽  
Cross Country

We tested whether the rate at which force is applied to the ground sets metabolic rates during classical-style roller skiing in four ways: 1) by increasing speed (from 2.5 to 4.5 m/s) during skiing with arms only, 2) by increasing speed (from 2.5 to 4.5 m/s) during skiing with legs only, 3) by changing stride rate (from 25 to 75 strides/min) at each of three speeds (3.0, 3.5, and 4.0 m/s) during skiing with legs only, and 4) by skiing with arms and legs together at three speeds (2.0–3.2 m/s, 1.5° incline). We determined net metabolic rates from rates of O2 consumption (gross O2 consumption − standing O2 consumption) and rates of force application from the inverse period of pole-ground contact [1/ t p(arms)] for the arms and the inverse period of propulsion [1/ t p(legs)] for the legs. During arm-and-leg skiing at different speeds, metabolic rates changed in direct proportion to rates of force application, while the net ground force to counteract friction and gravity (F) was constant. Consequently, metabolic rates were described by a simple equation (E˙metab=F ⋅ 1/ t p ⋅ C, where E˙metab is metabolic rates) with cost coefficients ( C) of 8.2 and 0.16 J/N for arms and legs, respectively. Metabolic rates predicted from net ground forces and rates of force application during combined arm-and-leg skiing agreed with measured metabolic rates within ±3.5%. We conclude that rates of ground force application to support the weight of the body and overcome friction set the energetic cost of skiing and that the rate at which muscles expend metabolic energy during weight-bearing locomotion depends on the time course of their activation.

Estimating instantaneous energetic cost during non-steady-state gait

2014 ◽  
Vol 117 (11) ◽  
pp. 1406-1415 ◽  
Author(s):  
Jessica C. Selinger ◽  
J. Maxwell Donelan
Keyword(s):  
Steady State ◽  
Energy Use ◽  
Mitochondrial Dynamics ◽  
Metabolic Cost ◽  
The Body ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Control Mechanisms ◽  
Input Output ◽  
Linear Differential

Respiratory measures of oxygen and carbon dioxide are routinely used to estimate the body's steady-state metabolic energy use. However, slow mitochondrial dynamics, long transit times, complex respiratory control mechanisms, and high breath-by-breath variability obscure the relationship between the body's instantaneous energy demands (instantaneous energetic cost) and that measured from respiratory gases (measured energetic cost). The purpose of this study was to expand on traditional methods of assessing metabolic cost by estimating instantaneous energetic cost during non-steady-state conditions. To accomplish this goal, we first imposed known changes in energy use (input), while measuring the breath-by-breath response (output). We used these input/output relationships to model the body as a dynamic system that maps instantaneous to measured energetic cost. We found that a first-order linear differential equation well approximates transient energetic cost responses during gait. Across all subjects, model fits were parameterized by an average time constant (τ) of 42 ± 12 s with an average R2 of 0.94 ± 0.05 (mean ± SD). Armed with this input/output model, we next tested whether we could use it to reliably estimate instantaneous energetic cost from breath-by-breath measures under conditions that simulated dynamically changing gait. A comparison of the imposed energetic cost profiles and our estimated instantaneous cost demonstrated a close correspondence, supporting the use of our methodology to study the role of energetics during locomotor adaptation and learning.

scholarly journals Torpor reduces predation risk by compensating for the energetic cost of antipredator foraging behaviours

2018 ◽  
Vol 285 (1893) ◽  
pp. 20182370 ◽  
Author(s):  
Christopher Turbill ◽  
Lisa Stojanovski
Keyword(s):  
Body Temperature ◽  
Energy Saving ◽  
Predation Risk ◽  
Energy Intake ◽  
Foraging Behaviour ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Behavioural Responses ◽  
Perceived Predation Risk ◽  
Starvation Risk

Foraging activity is needed for energy intake but increases the risk of predation, and antipredator behavioural responses, such as reduced activity, generally reduce energy intake. Hence, the mortality and indirect effects of predation risk are dependent on the energy requirements of prey. Torpor, a controlled reduction in resting metabolism and body temperature, is a common energy-saving mechanism of small mammals that enhances their resistance to starvation. Here we test the hypothesis that torpor could also reduce predation risk by compensating for the energetic cost of antipredator behaviours. We measured the foraging behaviour and body temperature of house mice in response to manipulation of perceived predation risk by adjusting levels of ground cover and starvation risk by 24 h food withdrawal every third day. We found that a voluntary reduction in daily food intake in response to lower cover (high predation risk) was matched by the extent of a daily reduction in body temperature. Our study provides the first experimental evidence of a close link between energy-saving torpor responses to starvation risk and behavioural responses to perceived predation risk. By reducing the risk of starvation, torpor can facilitate stronger antipredator behaviours. These results highlight the interplay between the capacity for reducing metabolic energy expenditure, optimal decisions about foraging behaviour and the life-history ecology of prey.

scholarly journals The high energetic cost of rapid force development in cyclic muscle contraction

2020 ◽  
Author(s):  
Tim J. van der Zee ◽  
Arthur D. Kuo
Keyword(s):  
Metabolic Rate ◽  
Muscle Contraction ◽  
Muscle Force ◽  
Force Production ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Average Force ◽  
Force Development ◽  
The Cost

AbstractMuscles consume metabolic energy for active movement, particularly when performing mechanical work or producing force. Less appreciated is the cost for activating and deactivating muscle quickly, which adds considerably to the overall cost of cyclic force production (Chasiotis et al., 1987). But the cost relative to mechanical work, which features in many movements, is unknown. We therefore tested whether fast activation-deactivation is costly compared to performing work or producing isometric force. We hypothesized that metabolic cost would increase with a proposed measure termed force-rate (rate of increase in muscle force) in cyclic tasks, separate from mechanical work or average force level. We tested humans (N = 9) producing cyclic knee extension torque against an isometric dynamometer (torque 22 N-m, cyclic waveform frequencies 0.5 – 2.5 Hz), while also quantifying the force and work of muscle fascicles against series elasticity (with ultrasonography), along with metabolic rate through respirometry. Net metabolic rate increased by more than fourfold (10.5 to 46.7 W) with waveform frequency. At high frequencies, the hypothesized force-rate cost accounted for nearly half (41%) of energy expenditure. This exceeded the cost for average force (17%) and was comparable to the cost for shortening work (42%). The energetic cost is explained by a simple first-order model of rate-limiting steps in muscle contraction, primarily crossbridge dynamics. The force-rate cost could contribute substantially to the overall cost of movements that require cyclic muscle activation, such as locomotion.Summary statementThe energetic cost of isometric muscle force production during cyclic muscle contraction increases sharply with cycle frequency and in proportion to the rate of force development

scholarly journals The high energetic cost of rapid force development in muscle

2021 ◽  
pp. jeb.233965
Author(s):  
Tim J. van der Zee ◽  
Arthur D. Kuo
Keyword(s):  
Metabolic Rate ◽  
Muscle Activation ◽  
Muscle Force ◽  
Force Production ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Average Force ◽  
Rate Of Increase ◽  
The Cost

Muscles consume metabolic energy for active movement, particularly when performing mechanical work or producing force. Less appreciated is the cost for activating muscle quickly, which adds considerably to the overall cost of cyclic force production (Chasiotis et al., 1987). But the cost magnitude relative to mechanical work, which features in many movements, is unknown. We therefore tested whether fast activation is costly compared to performing work or producing isometric force. We hypothesized that metabolic cost would increase with a proposed measure termed force-rate (rate of increase in muscle force) in cyclic tasks, separate from mechanical work or average force level. We tested humans (N=9) producing cyclic knee extension torque against an isometric dynamometer (torque 22 N-m, cyclic waveform frequencies 0.5 – 2.5 Hz), while also quantifying quadriceps muscle force and work against series elasticity (with ultrasonography), along with metabolic rate through respirometry. Net metabolic rate increased by more than fourfold (10.5 to 46.7 W) with waveform frequency. At high frequencies, the hypothesized force-rate cost accounted for nearly half (40%) of energy expenditure. This exceeded the cost for average force (17%) and was comparable to the cost for shortening work (43%). The force-rate cost is explained by additional active calcium transport necessary for producing forces at increasing waveform frequencies, due to rate-limiting dynamics of force production. The force-rate cost could contribute substantially to the overall cost of movements that require cyclic muscle activation, such as locomotion.

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