Reliability and discriminant validity of instrumented skateboarding-specific postural sway test

A preliminary study

Abstract

The rise of skateboarding, particularly its inclusion in the Olympics, highlights the need for tailored balance assessment protocols, a notable gap in current research. In this study, we explored a new skateboarding-specific postural sway test. 28 participants (15 skateboarders, 13 non-skateboarders) performed four balance tasks on a force plate. The tasks evaluated the Center of Pressure (CoP) movement in antero-posterior (AP) and medio-lateral (ML) directions, and CoP area. Reliability was measured using the intraclass correlation coefficient (ICC) for relative reliability, and coefficient of variation (CV) for absolute reliability. Relative reliability was moderate to excellent (ICC: CoP AP velocity 0.75-0.89; CoP ML velocity 0.78-0.88; CoP Area 0.82-0.89). Absolute reliability was generally not acceptable, with CV exceeding 10% for almost all variables in all tasks. Significant task effects were observed in CoP velocity and area (p < 0.001), with a moderate group × task interaction in CoP area (p = 0.024; η² = 0.12), but no significant group differences. The third task (bipedal stance on skateboard with eyes closed) nearly reached significance between groups (t = 1.89; p = 0.069). The study demonstrates good relative but limited absolute reliability and discriminant validity for the skateboard-specific sway test, questioning the usefulness of these tests and specificity of balance adaptations in skateboarding.