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Running up and down hills: some consequences of size
Science (New York, N.Y.)
|December 8, 1972
Summary
Small mammals like mice expend proportionally more energy running horizontally than large mammals like chimpanzees. However, the energy cost to run uphill is similar across species, making uphill running less costly for small mammals.
Area of Science:
- Biomechanics
- Comparative Physiology
- Locomotion Energetics
Background:
- Mammalian locomotion exhibits size-dependent energetic costs during horizontal running.
- Vertical running capabilities differ significantly between small and large mammals.
Purpose of the Study:
- To compare the energetic cost of vertical versus horizontal running in small and large mammals.
- To investigate the influence of body size on the energetic demands of uphill locomotion.
Main Methods:
- Comparative analysis of energy expenditure in mice and chimpanzees during level and incline running.
- Measurement of metabolic energy consumption per unit of body weight and distance.
Main Results:
- Mice (30g) expend ~8x more energy per unit body weight than chimpanzees (17.5kg) during level running.
- The additional energy cost to lift body weight vertically (uphill) is similar for both species (~15.5 J/kg/m).
- The relative increase in energy expenditure for uphill vs. horizontal running is ~1/8 for mice compared to chimpanzees.
Conclusions:
- Uphill running is proportionally less costly for small mammals than for large mammals.
- Energy recovery during downhill running is efficient (~90%) in both mice and chimpanzees.
- Body size is a critical factor modulating the energetic efficiency of mammalian locomotion across different terrains.