Courier service workers frequently push and pull delivery trolley with heavy objects while performing their duties. A serious social issue has arisen because of occupational injuries among delivery personnel in South Korea. There has been substantial research on pushing and pulling tasks, however, not enough studies have addressed courier delivery tasks. Experienced professional courier workers participated in this study. The study explores the characteristics of pushing and pulling tasks with commonly used delivery trolleys. Electromyography and subjective discomfort analyses were conducted to gain insights. 3DSSPP was used to analyze the instantaneous loads. The results revealed distinct muscle usage patterns in the upper body during cart pushing and pulling by couriers. Workers were unable to differentiate between muscle fatigue in different body parts and underestimated the actual workload in particular. Pull tasks require more muscle effort than push tasks regardless of trolley type. It was observed that hand trucks were generally the most efficient means of general package delivery.