The flexion and extension of human muscular doesn't only support the human's motion but it also could help in term of energy harvesting. Motion of the human body is capable to generate electrical energy with the support of suitable harvesting devices. This type of energy is very useful for those do not have access to the electrical power grid for prolonged duration. Biomechanical energy harvesting on this study will identify the most suitable joints to extract the optimum amount of energy without significant increase on human metabolic rate. Positive and negative energy from human lower extremity gait such as ankle, knee and hip for the young adult and elderly subjects are analyzed against the gait cycle during the walking phase on a flat surface. © 2017 IEEE.