Study on the relationship between muscle fatigue and motion sickness responses in different sitting postures under ship rocking conditions

In a ship rocking environment, muscle activity in different sitting postures may impact passenger balance and stability, thereby aggravating or alleviating symptoms of motion sickness. This study aims to explore the relationship between motion sickness induced by ship rolling and muscle activity in various sitting postures, with the goal of informing the optimization of ship seat designs to enhance passenger comfort. The research focuses on the angle of backrest inclination and head-neck position as key variables. Participants were seated on a six-degree-of-freedom platform simulating ship movements and rated their discomfort levels in different sitting postures while electromyographic (EMG) signals were collected from the sternocleidomastoid (SCM), upper trapezius muscles, and erector spinae muscles. The analysis investigated the correlation between muscle activity and motion sickness across different postures. The results indicate that a 22.5° reclined backrest angle minimizes motion sickness discomfort, while no significant correlation was found between head and neck position and motion sickness in this study, but the interaction between head and neck position and backrest angle needs further study. Differences in muscle activity were identified between motion-susceptible and non-susceptible individuals, with the former exhibiting higher activity in the SCM and upper trapezius muscles, leading to greater fatigue. Additionally, only the SCM showed opposite activity between men and women, while the changes in the upper trapezius and erector spinae muscles were basically the same. This study provides insights for optimizing ship seat design, contributing to the alleviation of motion sickness symptoms and enhancing passenger comfort. The findings hold significance for ship seat design and open new possibilities for the application of industrial design in the field of maritime engineering.