Platform simulated wave motions inhibit neuromuscular responses

BACKGROUND: Seafaring workers must contend with motions that could impact their work performance and safety. OBJECTIVE: To compare and analyze the neuromuscular responses to a stable immediate environment placed in a moving (simulated wave platform motions) extended environment. METHODS: Isometric maximum voluntary contraction (MVC) forces of the elbow flexors and leg extensors as well as electromyography (EMG) of the biceps brachii and vastus lateralis were recorded. The EMG activity of the triceps brachii, semitendonosis, internal obliques, and lower lumbar erector spinae muscles were also monitored during the upper and lower limb MVCs. Three types of rotational motion (pitch, roll and mixed, all combined with a linear heave motion) created by a motion platform were randomly allocated for 1 minute each. While securely strapped and seated with the platform moving, two MVCs each were performed for the right elbow flexors and right knee extensors at the beginning and at the end of the one-minute wave motion protocol. RESULTS: Platform motions impaired ( p< 0.0001) knee extension (pitch = −8%; roll = −13.4%; mixed = −13.5%) and elbow flexor MVC force (pitch = −21.1%; roll = −26.7%; mixed = −25.1%) compared to control conditions. Vastus lateralis EMG was reduced 13.3% with roll motions compared to control. CONCLUSIONS: Platform simulated wave motions can be detrimental to force production when the individual is strapped in a secure and stable seated position. Such impairments can impact the safety and work performance of employees on sea going vessels.