Reliability and discriminant validity of instrumented skateboarding-specific postural sway test: a preliminary study

PURPOSE: 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. METHODS: 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 the coefficient of variation (CV) for absolute reliability. RESULTS: 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 a skateboard with eyes closed) nearly reached significance between groups (t = 1.89; p = 0.069). CONCLUSION: 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 the specificity of balance adaptations in skateboarding.