Biomechanical and Physiological Limits to Animal Flight Performance

人们对动物运动表现和运动能力的内在限制知之甚少。一般来说，在动物运动中，已知的有氧代谢率最高的是飞行形式，尤其是蜂鸟和昆虫。达德利博士将研究蜂鸟和体重相当的昆虫飞行性能的生理和生物力学限制。实验气体混合物的氧气浓度和空气密度将同时变化，从而在空气动力学和生理上挑战悬停的蜂鸟和飞蛾。飞行性能的限制将通过确定空气密度和氧气浓度来评估，在这种情况下，这些动物不能再维持悬停飞行。同时测量氧气消耗将评估相关的最大代谢率，而空气动力学模型将应用于观察到的翼拍运动学，以估计飞行肌肉的机械动力的相关消耗。随后将实施一系列额外的实验，在等效空气密度下提供增强的氧气可用性，以验证扩散氧通量是这两个分类群最大有氧性能的限制步骤的假设。在这种情况下，氧气消耗率的增加将表明扩散限制了最大运动性能，而没有这种增加将表明呼吸系统内对流通量的限制，或飞行力学的生物力学限制。零假设预测飞蛾的气管呼吸最终将受到氧气可用性的限制，而蜂鸟的肺通气在氧气可用性增加的条件下不会显示出这种能量增强。更一般地说，这项研究将证明脊椎动物和昆虫呼吸系统在最大性能条件下的内在设计约束。

Dudley 9603736 Inherent limits to exercise performance an athletic capacity of animals are little-understood. For animal locomotion generally, the highest known rates of aerobic metabolism are found in flying forms, particularly among hummingbirds and insects. Dr. Dudley will examine the physiological and biomechanical limits to flight performance in hummingbirds and in insects of comparable body mass. Oxygen concentration and air density of experimental gas mixtures will be simultaneously variesd so as to aerodynamically and physiologically challenge hovering hummingbirds and moths. The limits to flight performance will be evaluated behaviorally by determining the air densities and oxygen concentration at which these animals can no longer sustain hovering flight. Simultaneous measurements of oxygen consumption will evaluate the associated maximal metabolic rates, while aerodynamic models will be applied to the observed wingbeat kinematics to estimate the associated expenditure of mechanical power by the flight muscle. An additional series of experiments will then be implemented that provide enhanced oxygen availability at equivalent air densities, so as to test the hypothesis that diffusive oxygen flux is the limiting step in maximum aerobic performance of these two taxa. Increased rates of oxygen consumption under such conditions will indicate that diffusive constraints limit maximum locomotor performance, whereas no such increase will suggest limits of convective flux within the respiratory system, or biomechanical constraints on flight mechanics. The null hypothesis predicts that the tracheal respiration of moths will ultimately be limited by oxygen availability, whereas the pulmonary-based ventilation of hummingbirds will show no such energetic enhancement under conditions of increased oxygen availaility. More generally, this research will demonstrate inherent design constraints of both vertebrate and insect resporatory systems under conditions of maximum performance.