The purpose of this research is to analyze the energetic features of loaded gait subjected to the trunk flexion change. The feature of gait is analyzed by comparing the impulse, momentums and mechanical works between normal and loaded gait. For analysis, human gait is modeled as a simple mechanical system. Typical simple mechanical system is the simplest walking model like inverted pendulum. Merit of simplest model is able to predict energetic features of human gait like impulse, momentum and mechanical work.
However, this model has a defect due to the assumption and simplification. It is because this model has in-stantaneous collision by simultaneous push-off and heel-strike impulses, so gravitational effect was ignored during a step-to-step transition. To work out this problem, Yeom proposed finite collision model for the double support phase of human walking. This model can analyze the gravitational effect on the center-of-gravity during the double support phase. Based on this model, energetic feature of loaded gait subjected to the trunk flexion change will be analyzed.
To analyze the human gait, experiment was performed with 7 subjects comprised of trained active-duty sol-diers 5 and graduate students discharged from active service 2. Through this, we measured the ground reaction forces and kinematic data and calculated the collision impulses and mechanical work.
The result shows mechanical work done during single support phase is always close to zero to minimize total net work. In other word, it means that human walk efficiently to minimize total net works in case of loaded gait. Furthermore, energy influx for walking occurs at double support phase. Therefore, it can be seen that most of the process is almost performed in the double support phase.