Development and validation of the Kradot Kop Test: a culturally grounded field-based assessment of restricted lower-limb power–endurance in Thai children aged 10–12 years

Introduction: School-based fitness assessment is commonly framed around standardized motor tasks that prioritize measurement precision but often overlook cultural relevance and student engagement, particularly in contexts where traditional movement practices remain central to children’s physical experience. Objective: This study aimed to develop and validate the Kradot Kop Test as a culturally grounded field-based assessment for evaluating restricted lower-limb power–endurance in Thai children aged 10 to 12 years. Methodology: A sequential research and development design was employed. Content validity was established through expert review. Reliability and concurrent validity were examined against established indicators of lower-limb strength and explosive power. Large-scale field testing was conducted to examine performance characteristics, feasibility, and age- and sex-related differentiation under authentic school conditions. Results: The Kradot Kop Test demonstrated excellent inter-rater reliability and good intra-rater reliability. Concurrent validity analysis revealed moderate-to-strong associations with standardized measures of lower-limb strength and power, confirming that the test captures a distinct hybrid construct of restricted lower-limb power–endurance. High feasibility ratings were reported by students and physical education teachers. Field-based results showed clear age- and sex-related performance differentiation. Discussion: Findings indicate that culturally embedded movement patterns can be systematically transformed into reliable and valid assessment tools while maintaining ecological relevance and pedagogical value. Conclusions: The Kradot Kop Test represents a sustainable and contextually meaningful assessment that bridges Thai cultural heritage with empirical sport science and supports inclusive physical education practice.