Body sway at sea for two visual tasks and three stance widths

Area of Science:

• Human kinetics
• Naval physiology
• Biomechanics

Background:

• Body sway on land is influenced by stance width and visual tasks.
• Crewmembers perform visual tasks while standing on ships, but sway at sea is understudied.
• Ship motion can impact postural stability.

Purpose of the Study:

• To investigate the influence of stance width and visual tasks on body sway kinematics at sea.
• To determine if factors affecting sway on land also affect sway during ship motion.

Main Methods:

• Participants stood on a force plate to measure center of pressure (COP) variability.
• Stance width was varied (5 cm, 17 cm, 30 cm).
• Visual tasks included an Inspection task (viewing white paper) and a Search task (counting letters).

Main Results:

• COP variability decreased during the Search task compared to the Inspection task.
• COP variability decreased with wider stances.
• The effect of stance width on sway was more pronounced at sea than on land.

Conclusions:

• Stance width and visual task nature influence postural sway at sea, similar to land-based studies.
• These factors are not suppressed by ship motion in mild sea states.
• Findings have implications for crew safety and performance in maritime environments.