A preliminary investigation of upper limb muscle activity during simulated Canadian forest harvesting operations

The forest industry is a major economic sector of Canada. While mechanized machines have reduced injuries workers suffered during manual operations, these machines have also created other musculoskeletal concerns. The purpose of this study was to obtain data regarding upper limb musculoskeletal stress during typical harvesting operations using surface electromyography (EMG).

Students currently training in a forest machine operations course were recruited for this study. Four operators (1 female and 3 males, mean age = 24.6 ± 13.4 years, mean height = 172.7 ± 4.6 cm, mean weight = 75.4 ± 27.4 kg) participated in this study.

Surface electrodes were placed over the muscles of the upper arm and shoulder to monitor muscular activity during Harvester Simulator operation. Operators were provided specific instructions and visual feedback. Data were collected over a two hours of operation.

Preliminary data suggests that while the movements used in the simulator do not require large force, they are repetitive and constant and can result in muscle fatigue.

The EMG data indicated signs of fatigue in several muscles of the upper arms. This preliminary data suggests that while operation of these machines does not require large force contractions, the continuous and repetitive nature of the work can result in muscular fatigue. This suggests that long term operation of mobile machines may result in fatigue and future studies should examine job design.