Design analysis has become an essential tool to ensure the outcome of the biomechanical harvesting device met the expected goal. Biomechanical energy harvesting has become a prominent research topic to substitute the huge and heavy commercialized batteries. Hence, a lot of limitations and challenges faced during the design stage of harvesting device. The major considerations are on the increased metabolic rate to carry the device and the electrical power harvested in given duration. The additional effort needed to carry the device at different joint locations is essential in ergonomics and it's a key factor to design wearable device. Analysis was carried out to derive the scope of human's metabolic rate with the motion speed and walking duration. This paper discusses the outcome which shows that longer duration with higher speed and lower device mass is essential for better performance. © 2021 IEEE.