Collaborative Research: Effects of speed and body size on the partitioning of energy use among the locomotor muscles in bipedal running
Richard L. Marsh and Steven Wickler Northeastern University and Cal State Poly University Pomona
Variation in locomotor mechanics and energetics with speed and body size has had a prominent role in formulating hypotheses regarding the determinants of the economy of running and walking. However, past studies have been hampered by not knowing how the metabolic energy use by the animal is partitioned among the individual muscles that are active during locomotion. The proposed work will use muscle blood flow to estimate the energy use by all the muscles used during walking and running in bipedal birds of different size. The energy consumption by individual muscles will be related to several aspects of the biomechanics to test hypotheses about how the mechanics and energetics are related, including the partitioning of energy use between swing and stance, the cost of force production by the muscles, and storage of energy in elastic tendons. The researchers predict that this work will have a substantial impact on understanding of the mechanics and energetics of walking and running in animals and humans. The proposed studies should contribute important data that can be used to modify existing models of the energetics of legged locomotion, or to formulate new models. Because the economy and basic mechanics of legged locomotion appear to share many features across a diverse array of animals, including humans, the results of this project are expected to be broadly applicable. In addition to improving our understanding of the biomechanics and energetics of walking and running, the results of this project will have potential implications for human health. Generalization is possible because animal and human locomotion share the same fundamental biomechanical problems and constraints. Because many types of invasive studies cannot be done on humans, the function of muscles in human locomotion is often predicted based on models using externally observable movements and forces measured in human locomotion combined with information from animal studies defining the basic properties of the locomotor system. This study should provide a significant benchmark for testing the validity of the types of models used in human studies. Because these models are also used to develop rehabilitative strategies for individuals with compromised locomotor function, information that results in improving the models has the potential to improve these strategies. The records of the two institutions collaborating on this project also indicate that the funding will have a significant positive impact on the scientific training of women and minority graduate and undergraduate students.
