Oxygen transport during exercise in large mammals. I. Adaptive variation in oxygen demand

Jones, James H.; Longworth, K. E.; Lindholm, Å.; Conley, Kevin E.; Karas, Richard H.; Kayar, Susan R.; Taylor, Curtis R.

doi:10.1152/jappl.1989.67.2.862

Cited by 128 publications

(83 citation statements)

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“…(2) At BMR, blood flow is distributed equitably through the (fractal) vascular tree to all organs of the body; at MMR, over 90% of blood flow is directed to contracting Among species with similar BMR, there are great differences in the capacity to increase MR in support of exercise, e.g. in athletic vs sedentary species Jones et al, 1989). In this paper we shall first critically review the existing data base for MMR scaling in mammals.…”

Section: Models and Hypotheses Of Mr Scalingmentioning

confidence: 99%

“…For example, in the size class of 25·kg the range of V O ∑ max is almost one order of magnitude between the goat on one hand and the pronghorn antelope on the other. This is related to differences in the aerobic exercise capacity of different species, which is higher in athletic mammals, such as horse, dog and pronghorn, compared to the majority of 'normal' or more sedentary species Jones et al, 1989;Lindstedt et al, 1991). These athletic species are marked by large, open triangles whereas small, filled triangles mark the 'normal' species; the separation is made on the grounds of a high mass-specific V O ∑ max of athletic species.…”

Section: The Scaling Of Mmrmentioning

confidence: 99%

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Exercise-induced maximal metabolic rate scales with muscle aerobic capacity

Weibel

Hoppeler

2005

Journal of Experimental Biology

268

279

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Maximal metabolic rate (MMR) is elicited by a welldefined dominant process: the energy needs of locomotor activity at its sustainable maximum during a run. In contrast, other forms of MR have a more complex origin. Basal metabolic rate (BMR) reflects the lowest need of energy at rest in a postprandial state under thermoneutral conditions. It is the energy used to run basic cell functions in a large variety of organs, such as maintaining cell potentials, driving the heart and circulation, synthetic and housekeeping functions of all sorts, and maintenance of body temperature. BMR and MMR thus define the span over which the metabolic rate of the organism can vary. Their definitions are unambiguous and, as such, they are reproducible. They reflect the performance of the organism under these specific test conditions, but are not conditions that occur usually in life. Natural forms of MR are intermediate. Field metabolic rate (FMR) reflects the timeaveraged MR elicited by all possible organismic functions at variable levels of activity, such as foraging or hunting for food, or digestion, and is commonly found to be about 4 times BMR. What is termed sustained MR refers to the metabolic rate that allows for maintaining body mass over longer time; it is a form of FMR mostly related to nutrient supply.Whereas BMR appears to depend essentially on body mass, MMR shows large inter-individual and inter-species variability, related to the degree of work or exercise capacity. It is typically about tenfold higher than BMR. Well-trained human athletes can achieve MMR up to 20 times higher than their BMR. Even greater variation is found in animals. Athletic species such as dogs or horses increase their MR by 30-fold from rest to maximal exercise, and in race horses this factor can rise to 50, as in the pronghorn antelope, the world's top athletic mammal.MMR reflects the limitation of oxidative metabolism of muscle cells. It is not sustainable for more than a few minutes because, under these limiting conditions, the incipient aerobic energy deficit must be covered by anaerobic glycolysis, which leads to lactate accumulation in the blood and thus to cessation of exercise.All forms of MR in mammals and other taxa show some scaling with body mass M b according to the allometric The logarithmic nature of the allometric equation suggests that metabolic rate scaling is related to some fractal properties of the organism. Two universal models have been proposed, based on (1) the fractal design of the vasculature and (2) the fractal nature of the 'total effective surface' of mitochondria and capillaries. According to these models, basal and maximal metabolic rates must scale as M 3/4 . This is not what we find. In 34 eutherian mammalian species (body mass M b ranging from 7·g to 500·kg) we found V O ∑ max to scale with the 0.872 (±0.029) power of body mass, which is significantly different from 3/4 power scaling. Integrated structure-function studies on a subset of eleven species (M b 20·g to 450·kg) show that the variation of V O ∑ max wit...

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Section: Models and Hypotheses Of Mr Scalingmentioning

confidence: 99%

Section: The Scaling Of Mmrmentioning

confidence: 99%

Exercise-induced maximal metabolic rate scales with muscle aerobic capacity

Weibel

Hoppeler

2005

Journal of Experimental Biology

268

279

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“…The relative heart mass of birds and mammals is typically between 0.5 and 1.5% of body mass while the average haemoglobin concentration for birds and mammals is around 15 g100 ml 71 blood (SchmidtNielsen 1984), so I will de¢ne a standard bird or mammal as one which has a relative heart mass of 1% of body mass and a haemoglobin concentration of 15 g100 ml 71 blood. are available for at least two species of running birds (Brackenbury et al 1981;Bundle et al 1999), four studies of £ying birds (Tucker 1968;Torre-Bueno & Larochelle 1978;Gessaman 1980;Wells 1993), two studies of £ying bats (Thomas & Suthers 1972;Carpenter 1985) and seven species of running mammals (Gleeson et al 1983;Karas et al 1987;Taylor et al 1987;Jones et al 1989), for which the values for V . O 2 are likely to be maximal.…”

Section: The V O 2max and Aerobic Scope Of Standard Birds And Mammamentioning

confidence: 99%

The maximum oxygen consumption and aerobic scope of birds and mammals: getting to the heart of the matter

Bishop

1999

Proc. R. Soc. Lond. B

168

143

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Resting or basal metabolic rates, compared across a wide range of organisms, scale with respect to body mass as approximately the 0.75 power. This relationship has recently been linked to the fractal geometry of the appropriate transport system or, in the case of birds and mammals, the blood vascular system. However, the structural features of the blood vascular system should more closely re£ect maximal aerobic metabolic rates rather than submaximal function. Thus, the maximal aerobic metabolic rates of birds and mammals should also scale as approximately the 0.75 power. A review of the literature on maximal oxygen consumption and factorial aerobic scope (maximum oxygen consumption divided by basal metabolic rate) suggests that body mass in£uences the capacity of the cardiovascular system to raise metabolic rates above those at rest. The results show that the maximum sustainable metabolic rates of both birds and mammals are similar and scale as approximately the 0.88 AE 0.02 power of body mass (and aerobic scope as approximately the 0.15 AE 0.05 power), when the measurements are standardized with respect to the di¡erences in relative heart mass and haemoglobin concentration between species. The maximum heart beat frequency of birds and mammals is predicted to scale as the 70.12 AE 0.02 power of body mass, while that at rest should scale as 70.27 AE 0.04.

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“…Schmidt-Nielsen 1984). Using values for cardiovascular variables from the literature (Gleeson et al 1983 ;Karas et al 1987 ;Taylor et al 1987 ;Jones et al 1989), from mammals during maximum running performance on a treadmill, I will estimate the function relating V} b,max of terrestrial mammals to M h , and consider the relevance of this function to birds and mammals during flight.…”

Section: Introductionmentioning

confidence: 99%

Heart mass and the maximum cardiac output of birds and mammals: implications for estimating the maximum aerobic power input of flying animals

Bishop

1997

Phil. Trans. R. Soc. Lond. B

127

165

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Empirical studies of cardiovascular variables suggest that relative heart muscle mass (relative M h ) is a good indicator of the degree of adaptive specialization for prolonged locomotor activities, for both birds and mammals. Reasonable predictions for the maximum oxygen consumption of birds during flight can be obtained by assuming that avian heart muscle has the same maximum physiological and biomechanical performance as that of terrestrial mammals. Thus, data on M h can be used to provide quantitative estimates for the maximum aerobic power input (aerobic P i, max ) available to animals during intense levels of locomotor activity. The maximum cardiac output of birds and mammals is calculated to scale with respect to M h (g) as 213 M h 0.88±0.04 (ml min −1 ), while aerobic P i,max is estimated to scale approximately as 11 M h 0.88±0.09 (W). In general, estimated inter–species aerobic P i,max , based on M h for all bird species (excluding hummingbirds), is calculated to scale with respect to body mass ( M b in kg) as 81 M b 0.82±0.11 (W). Comparison of family means for M h indicate that there is considerable diversity in aerobic capacity among birds and mammals, for example, among the medium to large species of birds the Tinamidae have the smallest relative M h (0.25 %) while the Otidae have unusually large relative M h (1.6 %). Hummingbirds have extremely large relative M h (2.28 %), but exhibit significant sexual dimorphism in their scaling of M h and flight muscle mass, so that when considering hummingbird flight performance it may be useful to control for sexual differences in morphology. The estimated scaling of aerobic P i,max (based on M h and M b in g) for male and female hummingbirds is 0.51 M b 0.83 ±0.07 and 0.44 M b 0.85± 0.11 (W), respectively. Locomotory muscles are dynamic structures and it might be anticipated that where additional energetic ‘costs’ occur seasonally (e.g. due to migratory fattening or the development of large secondary sexual characteristics) then the relevant cardiac and locomotor musculature might also be regulated seasonally. This is an important consideration, both due to the intrinsic interest of studying muscular adaptation to changes in energy demand, but also as a confounding variable in the practical use of heart rate to estimate the energetics of animals. Haemoglobin concentration (or haematocrit) may also be a confounding variable. Thus, it is concluded that data on the cardiovascular and flight muscle morphology of animals provides essential information regarding the behavioural, ecological and physiological significance of the flight performance of animals.

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Oxygen transport during exercise in large mammals. I. Adaptive variation in oxygen demand

Cited by 128 publications

References 0 publications

Exercise-induced maximal metabolic rate scales with muscle aerobic capacity

Exercise-induced maximal metabolic rate scales with muscle aerobic capacity

The maximum oxygen consumption and aerobic scope of birds and mammals: getting to the heart of the matter

Heart mass and the maximum cardiac output of birds and mammals: implications for estimating the maximum aerobic power input of flying animals

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