RUBENSON, J*; MARSH, R.L.; Biology Department, Northeastern University: Joint moments and powers during the swing-phase of running in the guinea fowl (Numida meleagris)

Although locomotor kinematics and segmental energetics have been analyzed across bipedal species, few comparative studies have adopted a traditional Newton-Euler dynamic analysis of locomotion. This type of analysis is fundamental to understanding the coordination and motor control of locomotion, as well as locomotor efficiency. Here we examine joint kinetics during the swing-phase of running in the guinea fowl using inverse dynamic modeling. Preliminary results indicate that a moderate hip flexion moment drives hip flexion throughout early- and mid-swing, followed by an extension moment that decelerates the thigh in preparation for toe-strike. During early swing, the knee has an extension moment that decelerates knee flexion. The knee has a negligible flexion moment during mid-swing, followed by a larger flexion moment towards the end of swing that slows the forward motion of the tibiotarsus. The ankle exhibits a flexion moment during the first half of the swing-phase and an extension moment during the latter half of swing, which drive ankle flexion and extension, respectively. These data are consistent with EMG data recorded previously in our laboratory, with the exception of knee extensor activity during mid-swing. Joint power analysis revealed that the hip and ankle produce the majority of the positive mechanical work of the swing-phase, whereas the knee does primarily negative work. Using inverse dynamic modeling we help reveal muscle function that is not obvious from kinematic analyses alone, such as the role of the hip-extensors and knee-flexors as brakes at the end of swing. Supported by NIH AR47337.