scholarly journals Mechanical work accounts for most of the energetic cost in human running

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
R. C. Riddick ◽  
A. D. Kuo
Keyword(s):  
Soft Tissue ◽  
Metabolic Cost ◽  
Energetic Cost ◽  
Joint Mechanics ◽  
Active Muscle ◽  
Muscle Work ◽  
Direct Measurements ◽  
Save Energy ◽  
Tissue Deformations ◽  
Human Running

AbstractThe metabolic cost of human running is not well explained, in part because the amount of work performed actively by muscles is largely unknown. Series elastic tissues such as tendon can save energy by performing work passively, but there are few direct measurements of the active versus passive contributions to work in running. There are, however, indirect biomechanical measures that can help estimate the relative contributions to overall metabolic cost. We developed a simple cost estimate for muscle work in humans running (N = 8) at moderate speeds (2.2–4.6 m/s) based on measured joint mechanics and passive dissipation from soft tissue deformations. We found that even if 50% of the work observed at the lower extremity joints is performed passively, active muscle work still accounts for 76% of the net energetic cost. Up to 24% of this cost compensates for the energy lost in soft tissue deformations. The estimated cost of active work may be adjusted based on assumptions of multi-articular energy transfer, elasticity, and muscle efficiency, but even conservative assumptions yield active work costs of at least 60%. Passive elasticity can reduce the active work of running, but muscle work still explains most of the overall energetic cost.

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.

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.

scholarly journals Soft tissue deformations explain most of the mechanical work variations of human walking

2021 ◽  
Author(s):  
Tim J. van der Zee ◽  
Arthur D. Kuo
Keyword(s):  
Soft Tissue ◽  
Soft Tissues ◽  
Metabolic Cost ◽  
Step Length ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Whole Body ◽  
Human Walking ◽  
Negative Work ◽  
Tissue Deformations

AbstractHumans perform mechanical work during walking, some by leg joints actuated by muscles, and some by passive, dissipative soft tissues. Dissipative losses must be restored by active muscle work, potentially in amounts sufficient to cost substantial metabolic energy. The most dissipative, and therefore costly, walking conditions might be predictable from the pendulum-like dynamics of the legs. If pendulum behavior is systematic, it may also predict the work distribution between active joints and passive soft tissues. We therefore tested whether the overall negative work of walking, and the fraction due to soft tissue dissipation, are both predictable by a pendulum model across a wide range of conditions. The model predicts whole-body negative work from the leading leg’s impact with ground (termed the Collision), to increase with the squared product of walking speed and step length. We experimentally tested this in humans (N = 9) walking in 26 different combinations of speed (0.7 – 2.0 m·s-1) and step length (0.5 – 1.1 m), with recorded motions and ground reaction forces. Whole-body negative Collision work increased as predicted (R2= 0.73), with a consistent fraction of about 63% (R2= 0.88) due to soft tissues. Soft tissue dissipation consistently accounted for about 56% of the variation in total whole-body negative work. During typical walking, active work to restore dissipative losses could account for 31% of the net metabolic cost. Soft tissue dissipation, not included in most biomechanical studies, explains most of the variation in negative work of walking, and could account for a substantial fraction of the metabolic cost.Summary statementSoft tissue deformations dissipate substantial energy during human walking, as predicted by a simple walking model.

scholarly journals Muscle-specific economy of force generation and efficiency of work production during human running

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sebastian Bohm ◽  
Falk Mersmann ◽  
Alessandro Santuz ◽  
Arno Schroll ◽  
Adamantios Arampatzis
Keyword(s):  
Vastus Lateralis ◽  
Mechanical Energy ◽  
Metabolic Cost ◽  
Operating Conditions ◽  
Force Generation ◽  
Effective Length ◽  
High Enthalpy ◽  
Muscle Work ◽  
Work Production ◽  
Human Running

Human running features a spring-like interaction of body and ground, enabled by elastic tendons that store mechanical energy and facilitate muscle operating conditions to minimize the metabolic cost. By experimentally assessing the operating conditions of two important muscles for running, the soleus and vastus lateralis, we investigated physiological mechanisms of muscle work production and muscle force generation. We found that the soleus continuously shortened throughout the stance phase, operating as work generator under conditions that are considered optimal for work production: high force-length potential and high enthalpy efficiency. The vastus lateralis promoted tendon energy storage and contracted nearly isometrically close to optimal length, resulting in a high force-length-velocity potential beneficial for economical force generation. The favorable operating conditions of both muscles were a result of an effective length and velocity-decoupling of fascicles and muscle-tendon unit, mostly due to tendon compliance and, in the soleus, marginally by fascicle rotation.

scholarly journals Metabolic cost of generating horizontal forces during human running

1999 ◽  
Vol 86 (5) ◽  
pp. 1657-1662 ◽  
Author(s):  
Young-Hui Chang ◽  
Rodger Kram
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Order Of Magnitude ◽  
Reaction Forces ◽  
The Cost ◽  
Support Body Weight ◽  
Human Running

Previous studies have suggested that generating vertical force on the ground to support body weight (BWt) is the major determinant of the metabolic cost of running. Because horizontal forces exerted on the ground are often an order of magnitude smaller than vertical forces, some have reasoned that they have negligible cost. Using applied horizontal forces (AHF; negative is impeding, positive is aiding) equal to −6, −3, 0, +3, +6, +9, +12, and +15% of BWt, we estimated the cost of generating horizontal forces while subjects were running at 3.3 m/s. We measured rates of oxygen consumption (V˙o 2) for eight subjects. We then used a force-measuring treadmill to measure ground reaction forces from another eight subjects. With an AHF of −6% BWt,V˙o 2 increased 30% compared with normal running, presumably because of the extra work involved. With an AHF of +15% BWt, the subjects exerted ∼70% less propulsive impulse and exhibited a 33% reduction inV˙o 2. Our data suggest that generating horizontal propulsive forces constitutes more than one-third of the total metabolic cost of normal running.

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).

Activity Patterns and Energetics of the Moth, Hyalophora Cecropia

1970 ◽  
Vol 53 (3) ◽  
pp. 611-627
Author(s):  
JAMES L. HANEGAN ◽  
JAMES EDWARD HEATH
Keyword(s):  
Activity Patterns ◽  
Balance Sheet ◽  
Adult Life ◽  
Metabolic Cost ◽  
Hormonal Control ◽  
Energetic Cost ◽  
Air Temperatures ◽  
Hyalophora Cecropia ◽  
Metabolic Expenditure ◽  
Maintenance Metabolism

1. The time of activity and the duration of active periods (flight) of moths of the species Hyalophora cecropia has been determined by monitoring thoracic temperature. 2. The metabolic cost of flight per day and per adult life has been determined directly by measuring O2 consumption and indirectly by analysis of cooling curves of individual moths. 3. An energy balance sheet has been derived which gives the metabolic cost of flight and maintenance (during torpor) over the insect's adult life. 4. The metabolic stores mobilized for daily activity appear to be fixed and independent of air temperature. This mobilization of fat stores may be under hormonal control. 5. It is metabolically more expensive for moths to be active at low air temperatures. The number and duration of active periods at low air temperatures is reduced, but, the metabolic expenditure for activity is equal to that of animals held at higher air temperatures. 6. Females have a smaller total energy reserve than males. The number of active periods per day is not significantly different between the sexes at any given temperature, but in females the active periods are significantly shorter in duration. 7. The flight speed has been determined, and estimates of the flight range per day and per adult life have been calculated. 8. The ecology of H. cecropia has been discussed with respect to the timing and duration of active periods, the range and speed of flight, and the energetic cost of flight and maintenance metabolism.

scholarly journals Multi-objective control in human walking: insight gained through simultaneous degradation of energetic and motor regulation systems

2019 ◽  
Vol 16 (158) ◽  
pp. 20190227
Author(s):  
Kirsty A. McDonald ◽  
Joseph P. Cusumano ◽  
Peter Peeling ◽  
Jonas Rubenson
Keyword(s):  
Energy Minimization ◽  
Metabolic Cost ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Leg Length ◽  
Multi Objective ◽  
Speed Regulation ◽  
Speed Error ◽  
Objective Control ◽  
Error Regulation

Minimization of metabolic energy is considered a fundamental principle of human locomotion, as demonstrated by an alignment between the preferred walking speed (PWS) and the speed incurring the lowest metabolic cost of transport. We aimed to (i) simultaneously disrupt metabolic cost and an alternate acute task requirement, namely speed error regulation, and (ii) assess whether the PWS could be explained on the basis of either optimality criterion in this new performance and energetic landscape. Healthy adults ( N = 21) walked on an instrumented treadmill under normal conditions and, while negotiating a continuous gait perturbation, imposed leg-length asymmetry. Oxygen consumption, motion capture data and ground reaction forces were continuously recorded for each condition at speeds ranging from 0.6 to 1.8 m s −1 , including the PWS. Both metabolic and speed regulation measures were disrupted by the perturbation ( p < 0.05). Perturbed PWS selection did not exhibit energetic prioritization (although we find some indication of energy minimization after motor adaptation). Similarly, PWS selection did not support prioritization of speed error regulation, which was found to be independent of speed in both conditions. It appears that, during acute exposure to a mechanical gait perturbation of imposed leg-length asymmetry, humans minimize neither energetic cost nor speed regulation errors. Despite the abundance of evidence pointing to energy minimization during normal, steady-state gait, this may not extend acutely to perturbed gait. Understanding how the nervous system acutely controls gait perturbations requires further research that embraces multi-objective control paradigms.

Activity-related constraints on overwintering young-of-the-year striped bass (Morone saxatilis)

2001 ◽  
Vol 79 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Thomas P Hurst ◽  
David O Conover
Keyword(s):  
Food Consumption ◽  
Striped Bass ◽  
Morone Saxatilis ◽  
Metabolic Cost ◽  
Hudson River ◽  
Energetic Cost ◽  
Energy Budgets ◽  
Swimming Velocity ◽  
Thermal Dependence ◽  
Young Of The Year

The importance of activity to overwintering fishes has received little attention. Activity imposes two constraints: maximum swimming speed limits habitats that can be occupied for short periods of time, while the metabolic cost of swimming limits the habitats that are suitable for long-term residence. We measured the energetic consequences of activity and maximum swimming speeds of young-of-the-year striped bass (Morone saxatilis), a species that overwinters in tidal estuaries. The energetic cost of swimming was determined from energy changes in unfed fish forced to swim at various speeds, while energy changes in fed fish provided a measure of their ability to offset swimming costs through feeding. In high-velocity treatments, mortality was size-dependent and appeared to be related to fatigue rather than to depletion of energy reserves. The energetic cost of swimming increased with swimming velocity, but fish increased food consumption and thereby met their metabolic needs. In a second experiment the thermal dependence of swimming capacity in winter-acclimated striped bass was measured. Swimming speeds increased with temperature, from 2.7 body lengths (BL)/s at 2°C to 4.8 BL/s at 8 and 11°C, but were considerably below observed flow velocities in the Hudson River, suggesting a need for behavioral or physical refuge from tidal currents. These results indicate the flexibility of energy budgets of overwintering fishes, allowing energetic stress to be minimized by reducing activity or elevating food-consumption rates when sufficient prey are available.

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