Energetics

@article{doi101152ajplegacy19742274848,
    author = "Taylor, C. and Shkolnik, A. and Dmi’el, R. and Baharav, D. and Borut, A.",
    title = "Running in cheetahs, gazelles, and goats: energy cost and limb configuration.",
    year = "1974",
    journal = "The American journal of physiology",
    url = "https://www.physiology.org/pb-assets/PDFs/2017-Legacy-1516816496183.pdf",
    doi = "10.1152/AJPLEGACY.1974.227.4.848",
    is_oa = "true",
    number = "4",
    pages = "848-850",
    semanticscholar_citation_count = "147",
    semanticscholar_id = "6f8635c20b3c41b3abce28a0e837b926eecbf878",
    volume = "227"
}

@article{taylor1974running,
    author = "Taylor, CR and Shkolnik, A and Dmi'el, R and Baharav, D and Borut, A",
    title = "Running in cheetahs, gazelles, and goats: energy cost and limb configuration",
    year = "1974",
    journal = "American Journal of Physiology-Legacy Content",
    url = "https://doi.org/10.1152/ajplegacy.1974.227.4.848",
    doi = "10.1152/ajplegacy.1974.227.4.848",
    number = "4",
    openalex = "W2327775516",
    pages = "848-850",
    volume = "227"
}

@article{fedak1979reappraisal,
    author = "Fedak, Michael A. and Seeherman, Howard J.",
    title = "Reappraisal of energetics of locomotion shows identical cost in bipeds and quadrupeds including ostrich and horse",
    year = "1979",
    journal = "Nature",
    url = "https://doi.org/10.1038/282713a0",
    doi = "10.1038/282713a0",
    number = "5740",
    openalex = "W2030556119",
    pages = "713-716",
    volume = "282",
    references = "doi101007bf00699624, doi101038272333a0, doi101086physzool50330155721, doi101126science1774045222, doi101126science17840651096, doi101126science1794069186, doi101126science835018, doi101152ajplegacy197021941104, doi1023072402280, taylor1974running"
}

@misc{fedak1979reappraisal1,
    author = "Fedak, M. A. and Seeherman, H. J",
    title = "Reappraisal of energetics of locomotion shows identical cost in bipeds and quadrupeds including ostrich and horse",
    year = "1979",
    howpublished = "Nature, v. 282, p. 713-716",
    note = "talkorigins\_source = {true}; raw\_reference = {Fedak, M. A., and Seeherman, H. J., 1979, Reappraisal of energetics of locomotion shows identical cost in bipeds and quadrupeds including ostrich and horse: Nature, v. 282, p. 713-716.}"
}

@article{taylor1979running2,
    author = "Taylor, C. R. et al",
    title = "Running in cheetahs, gazelles and goats",
    year = "1979",
    journal = "Energy cost and limb configuration: American Journal of Physiology, p. 848-850",
    note = "talkorigins\_source = {true}; raw\_reference = {Taylor, C. R. et al., 1979, Running in cheetahs, gazelles and goats: Energy cost and limb configuration: American Journal of Physiology, p. 848-850.}"
}

ABSTRACT The energetic cost of generating muscular force was studied by measuring the energetic cost of carrying loads in rats, dogs, humans, and horses for loads ranging between 7 and 27 % of body mass. Oxygen consumption increased in direct proportion to mass supported by the muscles, i.e. where is the oxygen consumption of the animal running with a load, is the oxygen consumption at the same speed without a load, mL is the mass of the animal plus the load, and m is the mass of the animal. Stride frequency, average number of feet on the ground over an integral number of strides, the time of contact of each foot relative to the other feet, and the average vertical acceleration during the contact phase were not measurably changed by the loads used in our experiments. From these observations we conclude that the average accelerations of the centre of mass of the animal are not changed by carrying the loads, and that muscular force developed by the animal increases in direct proportion to the load. It follows that the rate of energy utilization by muscles of an animal as it runs along the ground at any particular speed is nearly directly proportional to the force exerted by its muscles. The energetic cost of generating force over an interval of time (∫Fdt) increases markedly with running speed. An important consequence of the direct proportionality between increased oxygen consumption and mass of the load is that small animals expend much more energy to generate a given force at a given speed than large animals.

@article{doi101242jeb8619,
    author = "Taylor, C. Richard and Heglund, N. C. and McMahon, Thomas A. and Looney, Todd R.",
    title = "Energetic Cost of Generating Muscular Force During Running",
    year = "1980",
    journal = "Journal of Experimental Biology",
    abstract = "ABSTRACT The energetic cost of generating muscular force was studied by measuring the energetic cost of carrying loads in rats, dogs, humans, and horses for loads ranging between 7 and 27 \% of body mass. Oxygen consumption increased in direct proportion to mass supported by the muscles, i.e. where is the oxygen consumption of the animal running with a load, is the oxygen consumption at the same speed without a load, mL is the mass of the animal plus the load, and m is the mass of the animal. Stride frequency, average number of feet on the ground over an integral number of strides, the time of contact of each foot relative to the other feet, and the average vertical acceleration during the contact phase were not measurably changed by the loads used in our experiments. From these observations we conclude that the average accelerations of the centre of mass of the animal are not changed by carrying the loads, and that muscular force developed by the animal increases in direct proportion to the load. It follows that the rate of energy utilization by muscles of an animal as it runs along the ground at any particular speed is nearly directly proportional to the force exerted by its muscles. The energetic cost of generating force over an interval of time (∫Fdt) increases markedly with running speed. An important consequence of the direct proportionality between increased oxygen consumption and mass of the load is that small animals expend much more energy to generate a given force at a given speed than large animals.",
    url = "https://doi.org/10.1242/jeb.86.1.9",
    doi = "10.1242/jeb.86.1.9",
    openalex = "W2160457864"
}

Functional morphologists have traditionally regarded cost of locomotion as an important influence on the design of locomotor structures. If cost of locomotion is an important constraint in the natural selection of these structures, it should be possible to show that animals differing in limb morphology also differ in their locomotor costs. In previous experiments on three species of cursorial mammals differing considerably in limb structure, no such differences were detected. Since the factors that determine the rate of energy consumption of a running animal are not well understood, we felt that the effect of limb morphology on cost could best be examined in a system in which only the inertial properties of limbs were varied while other factors remained constant. Consequently, we have measured changes in the rate of energy consumption of running human subjects produced by artificial alterations in limb inertial properties. Other variables that might influence cost have been controlled. We found that the cost of adding a given mass to the limbs is significantly greater than adding it to the centre of mass and that this effect becomes more pronounced as the limb loads are moved distally. Thus a clear effect of limb mass and its distribution on cost of locomotion has been demonstrated.

@article{doi101242jeb1161363,
    author = "Myers, M J and Steudel, Karen",
    title = "Effect of Limb Mass and its Distribution on the Energetic Cost of Running",
    year = "1985",
    journal = "Journal of Experimental Biology",
    abstract = "Functional morphologists have traditionally regarded cost of locomotion as an important influence on the design of locomotor structures. If cost of locomotion is an important constraint in the natural selection of these structures, it should be possible to show that animals differing in limb morphology also differ in their locomotor costs. In previous experiments on three species of cursorial mammals differing considerably in limb structure, no such differences were detected. Since the factors that determine the rate of energy consumption of a running animal are not well understood, we felt that the effect of limb morphology on cost could best be examined in a system in which only the inertial properties of limbs were varied while other factors remained constant. Consequently, we have measured changes in the rate of energy consumption of running human subjects produced by artificial alterations in limb inertial properties. Other variables that might influence cost have been controlled. We found that the cost of adding a given mass to the limbs is significantly greater than adding it to the centre of mass and that this effect becomes more pronounced as the limb loads are moved distally. Thus a clear effect of limb mass and its distribution on cost of locomotion has been demonstrated.",
    url = "https://doi.org/10.1242/jeb.116.1.363",
    doi = "10.1242/jeb.116.1.363",
    openalex = "W2184225391",
    references = "taylor1974running"
}

Summary Monthly changes in abundance of Thomson's gazelles at 142 locations on the Serengeti Plains are presented over a 3½ year period. Numbers of gazelles on the eastern plains were strongly correlated with rainfall, whereas numbers in the central and western plains appeared to be related to other variables. Movements of female cheetahs and non‐resident male cheetahs corresponded closely to the movements of Thomson's gazelles but those of resident male cheetahs remained relatively independent of the gazelle migration.

@article{durant1988migration,
    author = "DURANT, S. M. and CARO, T. M. and COLLINS, D. A. and ALAWI, R. M. and FITZGIBBON, C. D.",
    title = "Migration patterns of Thomson's gazelles and cheetahs on the Serengeti Plains",
    year = "1988",
    journal = "African Journal of Ecology",
    abstract = "Summary Monthly changes in abundance of Thomson's gazelles at 142 locations on the Serengeti Plains are presented over a 3½ year period. Numbers of gazelles on the eastern plains were strongly correlated with rainfall, whereas numbers in the central and western plains appeared to be related to other variables. Movements of female cheetahs and non‐resident male cheetahs corresponded closely to the movements of Thomson's gazelles but those of resident male cheetahs remained relatively independent of the gazelle migration.",
    url = "https://doi.org/10.1111/j.1365-2028.1988.tb00978.x",
    doi = "10.1111/j.1365-2028.1988.tb00978.x",
    number = "4",
    openalex = "W2073312673",
    pages = "257-268",
    volume = "26",
    references = "doi101007bf00376974, doi101007bf00389015, doi101038scientificamerican077186, doi101111j143903101987tb00921x, doi101111j146979981987tb07455x, doi101126science191422292, doi101515mamm19673111, doi1023071296618, doi1023071942578, doi1023072259478"
}

@article{fitzgibbon1989a,
    author = "FitzGibbon, Clare D.",
    title = "A cost to individuals with reduced vigilance in groups of Thomson's Gazelles hunted by Cheetahs",
    year = "1989",
    journal = "Animal Behaviour",
    url = "https://doi.org/10.1016/0003-3472(89)90098-5",
    doi = "10.1016/0003-3472(89)90098-5",
    openalex = "W2026112692",
    pages = "508-510",
    volume = "37",
    references = "doi101007bf00302563, doi101007bf00376974, doi1010160022519382902892, doi101016s0003347274800497, doi101016s0003347280800327, doi101016s000334728180022x, doi101111j136520281968tb00906x, doi101163156853969x00053, doi1023071936082, openalexw1484524608"
}

The condition and age of Thomson's gazelles (Gazella thomsoni) killed by two species of predators were compared. The wild dog, a coursing predator, was predicted to take a greater proportion of young, old and sick animals than the cheetah, a stalker. As measured by the marrow fat content of limb bones, wild dogs captured more Thomson's gazelles in poor condition than cheetahs. This appeared to be a consequence of their preference for male gazelles, which were in worse condition than females. Cheetahs did not capture fewer young and old gazelles than wild dogs.

@article{fitzgibbon1989the,
    author = "FITZGIBBON, CLARE D. and FANSHAWE, J. H.",
    title = "The condition and age of Thomson's gazelles killed by cheetahs and wild dogs",
    year = "1989",
    journal = "Journal of Zoology",
    abstract = "The condition and age of Thomson's gazelles (Gazella thomsoni) killed by two species of predators were compared. The wild dog, a coursing predator, was predicted to take a greater proportion of young, old and sick animals than the cheetah, a stalker. As measured by the marrow fat content of limb bones, wild dogs captured more Thomson's gazelles in poor condition than cheetahs. This appeared to be a consequence of their preference for male gazelles, which were in worse condition than females. Cheetahs did not capture fewer young and old gazelles than wild dogs.",
    url = "https://doi.org/10.1111/j.1469-7998.1989.tb02528.x",
    doi = "10.1111/j.1469-7998.1989.tb02528.x",
    number = "1",
    openalex = "W2078427791",
    pages = "99-107",
    volume = "218",
    references = "doi101111j136520281968tb00906x, doi101111j136520281972tb01174x, doi101111j136520281982tb00278x, doi101428810104372, doi1023073145, doi1023073798360, openalexw1484524608, openalexw2033109056, openalexw2751121943"
}

Energetic requirements of under-water swimming in pygoscelid penguins were studied in Antarctica, using respirometry together with a 21 m long swim canal and externally attached devices recording the swimming speed and dive duration of unrestrained animals. Field measurements were compared with measurements of the hydrodynamic properties of an Adelie penguin model in a circulating water tank. Minimium transport costs during underwater swimming in Adelie (Pygoscelis adeliae), chinstrap (P. antarctica) and gentoo (P. papua) penguins averaged 4.9, 3.7 and 7.6 J kg-1 m-1, respectively, at their preferred swimming speeds of 2.2, 2.4 and 1.8 m s-1, allowing the birds to dive aerobically for 110, 130 and 93 s, respectively. From the swim canal measurements, we calculated a drag coefficient (CD) of 0.0368 for a typical Adelie penguin at 2.2 m s-1. This value is significantly lower than the CD of 0.04 of an ideal spindle and the CD of 0.0496 measured on the model in the laboratory. The reasons for this difference are discussed.

@article{doi101242jeb197165,
    author = "Culik, Boris and Wilson, Rory P. and Bannasch, R.",
    title = "Underwater Swimming At Low Energetic Cost By Pygoscelid Penguins",
    year = "1994",
    journal = "Journal of Experimental Biology",
    abstract = "Energetic requirements of under-water swimming in pygoscelid penguins were studied in Antarctica, using respirometry together with a 21 m long swim canal and externally attached devices recording the swimming speed and dive duration of unrestrained animals. Field measurements were compared with measurements of the hydrodynamic properties of an Adelie penguin model in a circulating water tank. Minimium transport costs during underwater swimming in Adelie (Pygoscelis adeliae), chinstrap (P. antarctica) and gentoo (P. papua) penguins averaged 4.9, 3.7 and 7.6 J kg-1 m-1, respectively, at their preferred swimming speeds of 2.2, 2.4 and 1.8 m s-1, allowing the birds to dive aerobically for 110, 130 and 93 s, respectively. From the swim canal measurements, we calculated a drag coefficient (CD) of 0.0368 for a typical Adelie penguin at 2.2 m s-1. This value is significantly lower than the CD of 0.04 of an ideal spindle and the CD of 0.0496 measured on the model in the laboratory. The reasons for this difference are discussed.",
    url = "https://doi.org/10.1242/jeb.197.1.65",
    doi = "10.1242/jeb.197.1.65",
    openalex = "W1896916792",
    references = "doi101126science835018"
}

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.

@article{doi101242jeb201192745,
    author = "Roberts, Thomas J. and Kram, Rodger and Weyand, Peter G. and Taylor, C. Richard",
    title = "Energetics of Bipedal Running: I. Metabolic Cost of Generating Force",
    year = "1998",
    journal = "Journal of Experimental Biology",
    abstract = "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.",
    url = "https://doi.org/10.1242/jeb.201.19.2745",
    doi = "10.1242/jeb.201.19.2745",
    openalex = "W2404689151",
    references = "doi101126science2251499"
}

Mammals re–entered the oceans less than 60 million years ago. The transition from a terrestrial to an aquatic lifestyle required extreme morphological and behavioural modifications concomitant with fundamentally different locomotor mechanisms for moving on land and through water. Energetic transport costs typically reflect such different locomotor modes, but can not be discerned from the fossil record. In this study the energetic challenges associated with changing from terrestrial to aquatic locomotion in primitive marine mammals are examined by comparing the transport, maintenance and locomotor costs of extant mammals varying in degree of aquatic specialization. The results indicate that running and swimming specialists have converged on an energetic optimum for locomotion. An allometric expression, COT TOT = 7.79 mass −0.29 (r 2 = 0.83, n = 6 species), describes the total cost of transport in J kg −1 m −1 for swimming marine mammals ranging in size from 21 kg to 15,000 kg. This relation is indistinguishable from that describing total transport costs in running mammals. In contrast, the transitional lifestyle of semi–aquatic mammals, similar to that of ancestral marine mammals, incurs costs that are 2.4–5.1 times higher than locomotor specialists. These patterns suggest that primitive marine mammals confronted an energetic hurdle before returning to costs reminiscent of their terrestrial ancestry, and may have reached an evolutionary limit for energetic optimization during swimming.

@article{doi101098rstb19990371,
    author = "Williams, Terrie M.",
    title = "The evolution of cost efficient swimming in marine mammals: limits to energetic optimization",
    year = "1999",
    journal = "Philosophical Transactions of the Royal Society B Biological Sciences",
    abstract = "Mammals re–entered the oceans less than 60 million years ago. The transition from a terrestrial to an aquatic lifestyle required extreme morphological and behavioural modifications concomitant with fundamentally different locomotor mechanisms for moving on land and through water. Energetic transport costs typically reflect such different locomotor modes, but can not be discerned from the fossil record. In this study the energetic challenges associated with changing from terrestrial to aquatic locomotion in primitive marine mammals are examined by comparing the transport, maintenance and locomotor costs of extant mammals varying in degree of aquatic specialization. The results indicate that running and swimming specialists have converged on an energetic optimum for locomotion. An allometric expression, COT TOT = 7.79 mass −0.29 (r 2 = 0.83, n = 6 species), describes the total cost of transport in J kg −1 m −1 for swimming marine mammals ranging in size from 21 kg to 15,000 kg. This relation is indistinguishable from that describing total transport costs in running mammals. In contrast, the transitional lifestyle of semi–aquatic mammals, similar to that of ancestral marine mammals, incurs costs that are 2.4–5.1 times higher than locomotor specialists. These patterns suggest that primitive marine mammals confronted an energetic hurdle before returning to costs reminiscent of their terrestrial ancestry, and may have reached an evolutionary limit for energetic optimization during swimming.",
    url = "https://doi.org/10.1098/rstb.1999.0371",
    doi = "10.1098/rstb.1999.0371",
    openalex = "W1979684572",
    references = "doi101126science1794069186"
}

The metabolic energy cost of walking is determined, to a large degree, by body mass, but it is not clear how body composition and mass distribution influence this cost. We tested the hypothesis that walking would be most expensive for obese women compared with obese men and normal-weight women and men. Furthermore, we hypothesized that for all groups, preferred walking speed would correspond to the speed that minimized the gross energy cost per distance. We measured body composition, maximal oxygen consumption, and preferred walking speed of 39 (19 class II obese, 20 normal weight) women and men. We also measured oxygen consumption and carbon dioxide production while the subjects walked on a level treadmill at six speeds (0.50-1.75 m/s). Both obesity and sex affected the net metabolic rate (W/kg) of walking. Net metabolic rates of obese subjects were only approximately 10% greater (per kg) than for normal-weight subjects, and net metabolic rates for women were approximately 10% greater than for men. The increase in net metabolic rate at faster walking speeds was greatest in obese women compared with the other groups. Preferred walking speed was not different across groups (1.42 m/s) and was near the speed that minimized gross energy cost per distance. Surprisingly, mass distribution (thigh mass/body mass) was not related to net metabolic rate, but body composition (% fat) was (r2= 0.43). Detailed biomechanical studies of walking are needed to investigate whether obese individuals adopt novel energy saving mechanisms during walking.

@article{doi101152japplphysiol007672005,
    author = "Browning, R. and Baker, Emily and Herron, Jessica A and Kram, Rodger",
    title = "Effects of obesity and sex on the energetic cost and preferred speed of walking",
    year = "2005",
    journal = "Journal of Applied Physiology",
    abstract = "The metabolic energy cost of walking is determined, to a large degree, by body mass, but it is not clear how body composition and mass distribution influence this cost. We tested the hypothesis that walking would be most expensive for obese women compared with obese men and normal-weight women and men. Furthermore, we hypothesized that for all groups, preferred walking speed would correspond to the speed that minimized the gross energy cost per distance. We measured body composition, maximal oxygen consumption, and preferred walking speed of 39 (19 class II obese, 20 normal weight) women and men. We also measured oxygen consumption and carbon dioxide production while the subjects walked on a level treadmill at six speeds (0.50-1.75 m/s). Both obesity and sex affected the net metabolic rate (W/kg) of walking. Net metabolic rates of obese subjects were only approximately 10\% greater (per kg) than for normal-weight subjects, and net metabolic rates for women were approximately 10\% greater than for men. The increase in net metabolic rate at faster walking speeds was greatest in obese women compared with the other groups. Preferred walking speed was not different across groups (1.42 m/s) and was near the speed that minimized gross energy cost per distance. Surprisingly, mass distribution (thigh mass/body mass) was not related to net metabolic rate, but body composition (\% fat) was (r2= 0.43). Detailed biomechanical studies of walking are needed to investigate whether obese individuals adopt novel energy saving mechanisms during walking.",
    url = "https://doi.org/10.1152/japplphysiol.00767.2005",
    doi = "10.1152/japplphysiol.00767.2005",
    openalex = "W2169036624",
    references = "doi101242jeb205233717"
}

The energy cost of terrestrial locomotion has been linked to the muscle forces generated to support body weight and swing the limbs. The LiMb model predicts these forces, and hence locomotor cost, as a function of limb length and basic kinematic variables. Here, I test this model in humans, goats and dogs in order to assess the performance of the LiMb model in predicting locomotor cost for bipeds and quadrupeds. Model predictions were compared to observed locomotor cost, measured via oxygen consumption, during treadmill trials performed over a range of speeds for both walking and running gaits. The LiMb model explained more of the variation in locomotor cost than other predictors, including contact time, Froude number and body mass. The LiMb model also accurately predicted the magnitude of vertical ground forces. Results suggest the LiMb model reliably links locomotor anatomy to force production and locomotor cost. Further, these data support the idea that limb length may underlie the scaling of locomotor cost for terrestrial animals.

@article{doi101242jeb02662,
    author = "Pontzer, Herman",
    title = "Predicting the energy cost of terrestrial locomotion: a test of the LiMb model in humans and quadrupeds",
    year = "2007",
    journal = "Journal of Experimental Biology",
    abstract = "The energy cost of terrestrial locomotion has been linked to the muscle forces generated to support body weight and swing the limbs. The LiMb model predicts these forces, and hence locomotor cost, as a function of limb length and basic kinematic variables. Here, I test this model in humans, goats and dogs in order to assess the performance of the LiMb model in predicting locomotor cost for bipeds and quadrupeds. Model predictions were compared to observed locomotor cost, measured via oxygen consumption, during treadmill trials performed over a range of speeds for both walking and running gaits. The LiMb model explained more of the variation in locomotor cost than other predictors, including contact time, Froude number and body mass. The LiMb model also accurately predicted the magnitude of vertical ground forces. Results suggest the LiMb model reliably links locomotor anatomy to force production and locomotor cost. Further, these data support the idea that limb length may underlie the scaling of locomotor cost for terrestrial animals.",
    url = "https://doi.org/10.1242/jeb.02662",
    doi = "10.1242/jeb.02662",
    openalex = "W2095248753",
    references = "doi101038346265a0, doi101111j146979981983tb04266x, doi101113jphysiol1977sp011866, doi101126science1107799, doi101126science2251499, doi101126science2740914, doi101146annurevph44030182000525, doi101242jeb205233717, doi101242jeb9711, doi104159harvard9780674184404"
}

@incollection{crossref2009a,
    title = "‘A Horse and Two Goats’",
    year = "2009",
    booktitle = "Another Canon",
    url = "https://doi.org/10.7135/upo9781843318040.005",
    doi = "10.7135/upo9781843318040.005",
    openalex = "W993431140",
    pages = "41-50"
}

The Svalbard rock ptarmigan, Lagopus muta hyperborea experiences extreme photoperiodic and climatic conditions on the Arctic archipelago of Svalbard. This species, however, is highly adapted to live in this harsh environment. One of the most striking adaptations found in these birds is the deposition, prior to onset of winter, of fat stores which may comprise up to 32% of body mass and are located primarily around the sternum and abdominal region. This fat, while crucial to the birds' survival, also presents a challenge in that the bird must maintain normal physiological function with this additional mass. In particular these stores are likely to constrain the respiratory system, as the sternum and pelvic region must be moved during ventilation and carrying this extra load may also impact upon the energetic cost of locomotion. Here we demonstrate that winter birds have a reduced cost of locomotion when compared to summer birds. A remarkable finding given that during winter these birds have almost twice the body mass of those in summer. These results suggest that Svalbard ptarmigan are able to carry the additional winter fat without incurring any energetic cost. As energy conservation is paramount to these birds, minimising the costs of moving around when resources are limited would appear to be a key adaptation crucial for their survival in the barren Arctic environment.

@article{doi101371journalpone0015490,
    author = "Lees, John and Nudds, Robert L. and Stokkan, Karl‐Arne and Folkow, Lars P. and Codd, Jonathan R.",
    title = "Reduced Metabolic Cost of Locomotion in Svalbard Rock Ptarmigan (Lagopus muta hyperborea) during Winter",
    year = "2010",
    journal = "PLoS ONE",
    abstract = "The Svalbard rock ptarmigan, Lagopus muta hyperborea experiences extreme photoperiodic and climatic conditions on the Arctic archipelago of Svalbard. This species, however, is highly adapted to live in this harsh environment. One of the most striking adaptations found in these birds is the deposition, prior to onset of winter, of fat stores which may comprise up to 32\% of body mass and are located primarily around the sternum and abdominal region. This fat, while crucial to the birds' survival, also presents a challenge in that the bird must maintain normal physiological function with this additional mass. In particular these stores are likely to constrain the respiratory system, as the sternum and pelvic region must be moved during ventilation and carrying this extra load may also impact upon the energetic cost of locomotion. Here we demonstrate that winter birds have a reduced cost of locomotion when compared to summer birds. A remarkable finding given that during winter these birds have almost twice the body mass of those in summer. These results suggest that Svalbard ptarmigan are able to carry the additional winter fat without incurring any energetic cost. As energy conservation is paramount to these birds, minimising the costs of moving around when resources are limited would appear to be a key adaptation crucial for their survival in the barren Arctic environment.",
    url = "https://doi.org/10.1371/journal.pone.0015490",
    doi = "10.1371/journal.pone.0015490",
    openalex = "W2112659042",
    references = "doi101021j150446a008, doi101038346265a0, doi101093acprofoso97801953106100010001, doi101093oso97801988303990010001, doi101098rstb19930050, doi101146annurevphysiol66032102115105, doi101152ajpregu19772335r243, doi1023071538741, doi1023071938580, doi103382ps0250096"
}

A large amount of variation in limb length between terrestrial mammals has been observed. Increased limb length may have evolved as a mechanism to reduce the cost of transport (COT), allowing for energy allocation to other important functions. The relationship between energy expenditure and limb length was investigated at the population level in the Longshanks mouse. This unique line of mice has on average 13% longer tibia than a randomly bred Control line. The hypothesis that the Longshanks mice would have a lower COT and increased stride length was tested here. The results show that the Longshanks mice (N=19) did have a lower COT (-24%), a longer stride (+7%) and a lower stride frequency (-5-7%) when compared to the Control mice (N=22). The results provide support for a relationship between limb length and locomotor performance and form an important contribution to the understanding of selective pressures shaping limb length.

@phdthesis{doi1011575prism28084,
    author = "Sparrow, Leah M.",
    title = "The effect of limb length on the cost of locomotion and gait in the Longshanks mouse.",
    year = "2015",
    booktitle = "PRISM (University of Calgary)",
    abstract = "A large amount of variation in limb length between terrestrial mammals has been observed. Increased limb length may have evolved as a mechanism to reduce the cost of transport (COT), allowing for energy allocation to other important functions. The relationship between energy expenditure and limb length was investigated at the population level in the Longshanks mouse. This unique line of mice has on average 13\% longer tibia than a randomly bred Control line. The hypothesis that the Longshanks mice would have a lower COT and increased stride length was tested here. The results show that the Longshanks mice (N=19) did have a lower COT (-24\%), a longer stride (+7\%) and a lower stride frequency (-5-7\%) when compared to the Control mice (N=22). The results provide support for a relationship between limb length and locomotor performance and form an important contribution to the understanding of selective pressures shaping limb length.",
    url = "https://doi.org/10.11575/prism/28084",
    doi = "10.11575/prism/28084",
    openalex = "W999631434",
    references = "doi101016s0014299903012743, doi101038292239a0, doi101038346265a0, doi101038nature03052, doi101093icb232347, doi101113jphysiol1949sp004363, doi101126science1774045222, doi101126science2740914, doi101152jappl1973352236, doi101152jappl1984564831"
}

BACKGROUND: Reducing the energetic cost of running seems the most feasible path to a sub-2-hour marathon. Footwear mass, cushioning, and bending stiffness each affect the energetic cost of running. Recently, prototype running shoes were developed that combine a new highly compliant and resilient midsole material with a stiff embedded plate. OBJECTIVE: The aim of this study was to determine if, and to what extent, these newly developed running shoes reduce the energetic cost of running compared with established marathon racing shoes. METHODS: 18 high-caliber athletes ran six 5-min trials (three shoes × two replicates) in prototype shoes (NP), and two established marathon shoes (NS and AB) during three separate sessions: 14, 16, and 18 km/h. We measured submaximal oxygen uptake and carbon dioxide production during minutes 3-5 and averaged energetic cost (W/kg) for the two trials in each shoe model. RESULTS: Compared with the established racing shoes, the new shoes reduced the energetic cost of running in all 18 subjects tested. Averaged across all three velocities, the energetic cost for running in the NP shoes (16.45 ± 0.89 W/kg; mean ± SD) was 4.16 and 4.01% lower than in the NS and AB shoes, when shoe mass was matched (17.16 ± 0.92 and 17.14 ± 0.97 W/kg, respectively, both p < 0.001). The observed percent changes were independent of running velocity (14-18 km/h). CONCLUSION: The prototype shoes lowered the energetic cost of running by 4% on average. We predict that with these shoes, top athletes could run substantially faster and achieve the first sub-2-hour marathon.

@article{doi101007s4027901708112,
    author = "Hoogkamer, Wouter and Kipp, Shalaya and Frank, Jesse H. and Farina, Emily M. and Luo, Geng and Kram, Rodger",
    title = "A Comparison of the Energetic Cost of Running in Marathon Racing Shoes",
    year = "2017",
    journal = "Sports Medicine",
    abstract = "BACKGROUND: Reducing the energetic cost of running seems the most feasible path to a sub-2-hour marathon. Footwear mass, cushioning, and bending stiffness each affect the energetic cost of running. Recently, prototype running shoes were developed that combine a new highly compliant and resilient midsole material with a stiff embedded plate. OBJECTIVE: The aim of this study was to determine if, and to what extent, these newly developed running shoes reduce the energetic cost of running compared with established marathon racing shoes. METHODS: 18 high-caliber athletes ran six 5-min trials (three shoes × two replicates) in prototype shoes (NP), and two established marathon shoes (NS and AB) during three separate sessions: 14, 16, and 18 km/h. We measured submaximal oxygen uptake and carbon dioxide production during minutes 3-5 and averaged energetic cost (W/kg) for the two trials in each shoe model. RESULTS: Compared with the established racing shoes, the new shoes reduced the energetic cost of running in all 18 subjects tested. Averaged across all three velocities, the energetic cost for running in the NP shoes (16.45 ± 0.89 W/kg; mean ± SD) was 4.16 and 4.01\% lower than in the NS and AB shoes, when shoe mass was matched (17.16 ± 0.92 and 17.14 ± 0.97 W/kg, respectively, both p < 0.001). The observed percent changes were independent of running velocity (14-18 km/h). CONCLUSION: The prototype shoes lowered the energetic cost of running by 4\% on average. We predict that with these shoes, top athletes could run substantially faster and achieve the first sub-2-hour marathon.",
    url = "https://doi.org/10.1007/s40279-017-0811-2",
    doi = "10.1007/s40279-017-0811-2",
    openalex = "W2770125989",
    references = "doi101126science2740914"
}