Speed-Related Energy Flow and Joint Function Change During Human Walking

During human walking, mechanical energy transfers between segments via joints. Jointmechanics of the human body are coordinated with each other to adapt to speedchange. The aim of this study is to analyze the functional behaviors of major joints duringwalking, and how joints and segments alter walking speed during different periods(collision, rebound, preload, and push-off) of stance phase. In this study, gait experimentwas performed with three different self-selected speeds. Mechanical works of joints andsegments were determined with collected data. Joint function indices were calculatedbased on net joint work. The results show that the primary functional behaviors ofjoints would not change with altering walking speed, but the function indices mightbe changed slightly (e.g., strut functions decrease with increasing walking speed). Waistacts as strut during stance phase and contributes to keep stability during collision whenwalking faster. Knee of stance leg does not contribute to altering walking speed. Hip and ankle absorb more mechanical energy to buffer the strike during collision with increasing walking speed. What is more, hip and ankle generate more energy during push-off with greater motion to push distal segments forward with increasing walking speed. Ankle also produces more mechanical energy during push-off to compensate the increased heel-strike collision of contralateral leg during faster walking. Thus, human may utilize the cooperation of hip and ankle during collision and push-off to alter walking speed. These findings indicate that speed change in walking leads to fundamental changes to joint mechanics.