Carello, C. A.*; Scheunemann, T. L.; Heitmann, D. M.: How body size affects the metabolic efficiency and lower limb joint kinematics of quail running on an incline

The majority of studies dealing with bipedal locomotion on varying surface grades have focused on humans. Thus, little is known about the relationship between body mass and efficiency of locomotion for running on inclines in non-human bipeds. In order to quantify this relationship in quail we used oxygen consumption analysis to determine the efficiency of incline running in small Button Quail (43g) and large Mountain Quail (211g). We found that Mountain Quail were metabolically more efficient than Button Quail when running uphill. In an attempt to explain the mechanisms responsible for this relationship between body mass and efficiency, we then conducted kinematic analysis on the hip, knee and ankle joints for level and incline running. We found that the range of motion for extension of all lower limb joints increased on an incline. We also found that there was a relatively greater increase in the extension of the limb joints in the smaller Button Quail when compared to the larger Mountain Quail. Extension of the lower limb joints occurs during the acceleration phase of the step and this is therefore considered the energetically costly phase of the step. Thus, smaller animals incur a reduction in metabolic efficiency because their lower limb joints must undergo a greater range of motion during the most energetically expensive phase of the step.