The metabolic cost of swimming in marine homeotherms.

1997 ◽  
Vol 200 (3) ◽  
pp. 531-542 ◽  
Author(s):  
A T Hind ◽  
W S Gurney
Keyword(s):  
Metabolic Rate ◽  
Metabolic Cost ◽  
Hydrodynamic Drag ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Minke Whales ◽  
Free And Forced Convection ◽  
Phocid Seals ◽  
Using Data ◽  
The Cost

This paper describes a model of the metabolic cost of swimming in pinnipeds and its application to other marine homeotherms. The model takes account of both hydrodynamic and thermal processes. The thermal component incorporates both free and forced convection and takes account of the effect of hair on free convection. Using data from the literature to evaluate all but two of the parameters, we apply the model to metabolic rate data on phocid seals, otariids (sea lions), penguins and minke whales. We show that the model is able to reproduce two unusual features of the data; namely, a very rapid increase in metabolic rate at low velocities and an overall rise in metabolic rate with velocity which is slower than the rise in hydrodynamic drag force. The work shows the metabolic costs of propulsion and thermoregulation in a swimming homeotherm to be interlinked and suggests differing costs of propulsion for different modes of swimming. This is potentially of ecological significance since the swimming speed that minimises the cost of transport for an animal will change with changes in water temperature.

scholarly journals Energetics of terrestrial locomotion of the platypus Ornithorhynchus anatinus

2001 ◽  
Vol 204 (4) ◽  
pp. 797-803 ◽  
Author(s):  
F.E. Fish ◽  
P.B. Frappell ◽  
R.V. Baudinette ◽  
P.M. MacFarlane
Keyword(s):  
Metabolic Rate ◽  
Metabolic Cost ◽  
Standard Metabolic Rate ◽  
Cost Of Transport ◽  
Terrestrial Locomotion ◽  
Terrestrial Mammals ◽  
Video Recordings ◽  
Ornithorhynchus Anatinus ◽  
The Cost ◽  
Limb Structure

The platypus Ornithorhynchus anatinus Shaw displays specializations in its limb structure for swimming that could negatively affect its terrestrial locomotion. Platypuses walked on a treadmill at speeds of 0.19-1.08 m × s(−1). Video recordings were used for gait analysis, and the metabolic rate of terrestrial locomotion was studied by measuring oxygen consumption. Platypuses used walking gaits (duty factor >0.50) with a sprawled stance. To limit any potential interference from the extensive webbing on the forefeet, platypuses walk on their knuckles. Metabolic rate increased linearly over a 2.4-fold range with increasing walking speed in a manner similar to that of terrestrial mammals, but was low as a result of the relatively low standard metabolic rate of this monotreme. The dimensionless cost of transport decreased with increasing speed to a minimum of 0.79. Compared with the cost of transport for swimming, the metabolic cost for terrestrial locomotion was 2.1 times greater. This difference suggests that the platypus may pay a price in terrestrial locomotion by being more aquatically adapted than other semi-aquatic or terrestrial mammals.

Hydrodynamic drag in steller sea lions (Eumetopias jubatus)

2000 ◽  
Vol 203 (12) ◽  
pp. 1915-1923 ◽  
Author(s):  
L.L. Stelle ◽  
R.W. Blake ◽  
A.W. Trites
Keyword(s):  
Minimum Cost ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
California Sea Lions ◽  
Cost Of Transport ◽  
Sea Lions ◽  
Drag Forces ◽  
The Individual

Drag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from ‘deceleration during glide’ measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5×10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a ‘laminar’ profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(−)(1) or 1.2-1.5 body lengths s(−)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(−)(1) based on the minimum cost of transport for California sea lions.

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 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.

The cost of transport of human running is not affected, as in walking, by wide acceleration/deceleration cycles

2013 ◽  
Vol 114 (4) ◽  
pp. 498-503 ◽  
Author(s):  
Alberto E. Minetti ◽  
Paolo Gaudino ◽  
Elena Seminati ◽  
Dario Cazzola
Keyword(s):  
Field Experiments ◽  
Metabolic Cost ◽  
Constant Speed ◽  
Metabolic Energy ◽  
Recent Theory ◽  
Cost Of Transport ◽  
Unit Distance ◽  
The Cost ◽  
Speed Fluctuations ◽  
Human Running

Although most of the literature on locomotion energetics and biomechanics is about constant-speed experiments, humans and animals tend to move at variable speeds in their daily life. This study addresses the following questions: 1) how much extra metabolic energy is associated with traveling a unit distance by adopting acceleration/deceleration cycles in walking and running, with respect to constant speed, and 2) how can biomechanics explain those metabolic findings. Ten males and ten females walked and ran at fluctuating speeds (5 ± 0, ± 1, ± 1.5, ± 2, ± 2.5 km/h for treadmill walking, 11 ± 0, ± 1, ± 2, ± 3, ± 4 km/h for treadmill and field running) in cycles lasting 6 s. Field experiments, consisting of subjects following a laser spot projected from a computer-controlled astronomic telescope, were necessary to check the noninertial bias of the oscillating-speed treadmill. Metabolic cost of transport was found to be almost constant at all speed oscillations for running and up to ±2 km/h for walking, with no remarkable differences between laboratory and field results. The substantial constancy of the metabolic cost is not explained by the predicted cost of pure acceleration/deceleration. As for walking, results from speed-oscillation running suggest that the inherent within-stride, elastic energy-free accelerations/decelerations when moving at constant speed work as a mechanical buffer for among-stride speed fluctuations, with no extra metabolic cost. Also, a recent theory about the analogy between sprint (level) running and constant-speed running on gradients, together with the mechanical determinants of gradient locomotion, helps to interpret the present findings.

scholarly journals Simulated hemiparesis increases optimal spatiotemporal gait asymmetry but not metabolic cost

2021 ◽  
Author(s):  
Russell T Johnson ◽  
Nicholas August Bianco ◽  
James Finley
Keyword(s):  
Gait Speed ◽  
Metabolic Cost ◽  
The Body ◽  
Musculoskeletal Modeling ◽  
Cost Of Transport ◽  
Gait Patterns ◽  
Post Stroke ◽  
The Cost ◽  
Future Work ◽  
Isometric Muscle

Several neuromuscular impairments, such as weakness (hemiparesis), occur after an individual has a stroke, and these impairments primarily affect one side of the body more than the other. Predictive musculoskeletal modeling presents an opportunity to investigate how a specific impairment affects gait performance post-stroke. Therefore, our aim was to use to predictive simulation to quantify the spatiotemporal asymmetries and changes to metabolic cost that emerge when muscle strength is unilaterally reduced. We also determined how forced spatiotemporal symmetry affects metabolic cost. We modified a 2-D musculoskeletal model by uniformly reducing the peak isometric muscle force in all muscles unilaterally. We then solved optimal control simulations of walking across a range of speeds by minimizing the sum of the cubed muscle excitations across all muscles. Lastly, we ran additional optimizations to test if reducing spatiotemporal asymmetry would result in an increase in metabolic cost. Our results showed that the magnitude and direction of effort-optimal spatiotemporal asymmetries depends on both the gait speed and level of weakness. Also, the optimal metabolic cost of transport was 1.25 m/s for the symmetrical and 20% weakness models but slower (1.00 m/s) for the 40% and 60% weakness models, suggesting that hemiparesis can account for a portion of the slower gait speed seen in people post-stroke. Adding spatiotemporal asymmetry to the cost function resulted in small increases (~4%) in metabolic cost. Overall, our results indicate that spatiotemporal asymmetry may be optimal for people post-stroke, who have asymmetrical neuromuscular impairments. Additionally, the effect of speed and level of weakness on spatiotemporal asymmetry may explain the well-known heterogenous distribution of spatiotemporal asymmetries observed in the clinic. Future work could extend our results by testing the effects of other impairments on optimal gait strategies, and therefore build a more comprehensive understanding of the gait patterns in people post-stroke.

Energetics of swimming by the platypus Ornithorhynchus anatinus: metabolic effort associated with rowing.

1997 ◽  
Vol 200 (20) ◽  
pp. 2647-2652 ◽  
Author(s):  
F E Fish ◽  
R V Baudinette ◽  
P B Frappell ◽  
M P Sarre
Keyword(s):  
Metabolic Rate ◽  
Water Current ◽  
Transport Costs ◽  
Cost Of Transport ◽  
Aquatic Locomotion ◽  
Ornithorhynchus Anatinus ◽  
Thrust Generation ◽  
The Cost ◽  
High Thrust ◽  
Aquatic Mammals

The metabolism of swimming in the platypus Ornithorhynchus anatinus Shaw was studied by measurement of oxygen consumption in a recirculating water flume. Platypuses swam against a constant water current of 0.45-1.0 ms-1. Animals used a rowing stroke and alternated bouts of surface and submerged swimming. Metabolic rate remained constant over the range of swimming speeds tested. The cost of transport decreased with increasing velocity to a minimum of 0.51 at 1.0 ms-1. Metabolic rate and cost of transport for the platypus were lower than values for semiaquatic mammals that swim at the water surface using a paddling mode. However, relative to transport costs for fish, the platypus utilized energy at a similar level to highly derived aquatic mammals that use submerged swimming modes. The efficient aquatic locomotion of the platypus results from its specialised rowing mode in conjunction with enlarged and flexible forefeet for high thrust generation and a behavioral strategy that reduces drag and energy cost by submerged swimming.

scholarly journals The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance

2021 ◽  
Author(s):  
Patrick W. Franks ◽  
Gwendolyn M. Bryan ◽  
Ricardo Reyes ◽  
Meghan P. O'Donovan ◽  
Karen N. Gregorczyk ◽  
...  
Keyword(s):  
Metabolic Cost ◽  
Knee Extension ◽  
Cost Of Transport ◽  
Loop Optimization ◽  
Human In The Loop ◽  
Lower Limb Exoskeleton ◽  
Walking Performance ◽  
Ankle Exoskeleton ◽  
The Cost ◽  
Hip Extension

For exoskeletons to be successful in real-world settings, they will need to be effective across a variety of terrains, including on inclines. While some single-joint exoskeletons have assisted incline walking, recent successes in level-ground assistance suggest that greater improvements may be possible by optimizing assistance of the whole leg. To understand how exoskeleton assistance should change with incline, we used human-in-the-loop optimization to find whole-leg exoskeleton assistance torques that minimized metabolic cost on a range of grades. We optimized assistance for three expert, able-bodied participants on 5 degree, 10 degree and 15 degree inclines using a hip-knee-ankle exoskeleton emulator. For all assisted conditions, the cost of transport was reduced by at least 50% relative to walking in the device with no assistance, a large improvement to walking that is comparable to the benefits of whole-leg assistance on level-ground. This corresponds to large absolute reductions in metabolic cost, with the most strenuous conditions reduced by 4.9 W/kg, more than twice the entire energy cost of level walking. Optimized extension torque magnitudes and exoskeleton power increased with incline, with hip extension, knee extension and ankle plantarflexion often growing as large as allowed by comfort-based limits. Applied powers on steep inclines were double the powers applied during level-ground walking, indicating that larger exoskeleton power may be optimal in scenarios where biological powers and costs are higher. Future exoskeleton devices can be expected to deliver large improvements in walking performance across a range of inclines, if they have sufficient torque and power capabilities.

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.

Flight Speed and Directional Responses to Wind by Migrating Canada Geese

The Auk ◽  
1984 ◽  
Vol 101 (2) ◽  
pp. 342-348 ◽  
Author(s):  
Michael L. Wege ◽  
Dennis G. Raveling
Keyword(s):  
Metabolic Rate ◽  
Wind Direction ◽  
Time Of Flight ◽  
Weather Conditions ◽  
Canada Geese ◽  
Cost Of Transport ◽  
Wind Drift ◽  
Visual Reference ◽  
The Cost ◽  
Goal Direction

Abstract We monitored headings, flight speeds, and time of flight of nine transmittertagged giant Canada geese (Branta canadensis maxima) during 10 different autumn migration flights during which data on wind directions and speeds were also available. Destination of these individuals was known because of previous observations of the same birds. This enabled us to evaluate their headings with respect to wind drift. As the magnitude of the following component of the wind increased, air speeds of migrating geese declined while ground speeds were not significantly changed. Therefore, the cost of transport over the ground, and probably metabolic rate, were minimized. Headings of migrant geese varied systematically and significantly with wind direction, but track directions did not deviate significantly from the goal direction. Thus, the geese compensated for wind drift. Visual reference to landmarks may have been the cue used to correct for drift, as weather conditions were such that geese could see the ground.

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