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Bioenergetics of Exercising Humans

  1. George A. Brooks

Published Online: 1 JAN 2012

DOI: 10.1002/cphy.c110007

Comprehensive Physiology

Comprehensive Physiology

How to Cite

Brooks, G. A. 2012. Bioenergetics of Exercising Humans. Comprehensive Physiology. 2:537–562.

Author Information

  1. Department of Integrative Biology, University of California, Berkeley, California

Publication History

  1. Published Online: 1 JAN 2012


Human muscles, limbs and supporting ventilatory, cardiovascular, and metabolic systems are well adapted for walking, and there is reasonable transfer of efficiency of movement to bicycling. Our efficiency and economy of movement of bipedal walking (≈30%) are far superior to those of apes. This overall body efficiency during walking and bicycling represents the multiplicative interaction of a phosphorylative coupling efficiency of ≈60%, and a mechanical coupling efficiency of ≈50%. These coupling efficiencies compare well with those of other species adapted for locomotion. We are capable runners, but our speed and power are inferior to carnivorous and omnivorous terrestrial mammalian quadrupeds because of biomechanical and physiological constraints. But, because of our metabolic plasticity (i.e., the ability to switch among carbohydrate (CHO)- and lipid-derived energy sources) our endurance capacity is very good by comparison to most mammals, but inferior to highly adapted species such as wolves and migratory birds. Our ancestral ability for hunting and gathering depends on strategy and capabilities in the areas of thermoregulation, and metabolic plasticity. Clearly, our competitive advantage of survival in the biosphere depends in intelligence and behavior. Today, those abilities that served early hunter-gatherers make for interesting athletic competitions due to wide variations in human phenotypes. In contemporary society, the stresses of regular physical exercise serve to minimize morbidities and mortality associated with physical inactivity, overnutrition, and aging. © 2012 American Physiological Society. Compr Physiol 2:537-562, 2012.