Deep-Sea Port Crane Operators’ Muscle Fatigue on Low Back and Shoulder: A Primary Exploration for Occupational Health and Safety Purposes

Global trade heavily relies on ocean logistics shipping. Deep-sea port crane operators are one of the frontline workers who work around the clock to achieve this goal. This study aimed to investigate muscle fatigue development using muscle strength test as a primary tool in occupational health and safety purposes. Twenty-six of them participated in the study. Only low back and shoulder (right) were tested for the maxi- mum voluntary contraction before and after the routine 4 h work session. Results significantly revealed the occurrence of muscle fatigues development (p < 0.05) which indicated through the decrease of maximum voluntary contraction after the work session: 108.3 ± 38.3 declining to 95.4 ± 40.1 kg for the low back (p = 0.000) and 59.9 ± declining to 51.9 ± 12.3 kg for the right shoulder (p = 0.001). Shoulder (right) in this study showed higher differential percentage of the maximum voluntary contraction with the value of 14.7 over 11.9% from the low back. This might have been due to the muscle loading transfer, that shifted from the low back to the shoulder, since the low back might have already been in musculoskeletal problem. This simple assessment tool, as a primary exploration, proved to be practical in an implementation on the occupational safety and health intervention.