Juggling skill acquisition through air-toss and ground-bounce practice in college students: A study protocol for the TuJuggling cluster-randomised trial

Introduction: Practice organization is vital for motor acquisition, yet pragmatic evidence on how instructional constraints shape learning in authentic settings remains scarce. The TuJuggling protocol establishes a standardised assessment and training framework for complex bimanual skills in novices using an ecological dynamics perspective. Methods: In this cluster-randomised crossover trial, registered on ClinicalTrials.gov (Identifier: NCT07528924), 200 students will complete two 4-week juggling interventions: air-toss (A) and floor-rebound (B), separated by a 1-week washout. The primary outcome is a Global Composite Score (40 tasks) across stable (floor) and unstable (BOSU) surfaces. Secondary outcomes include cognitive functions (attentional/inhibitory control, visuospatial memory, and working memory), handgrip strength, and psychological factors (flow and affect). Assessments occur at baseline and after each intervention period. Results: Data will be analysed using linear mixed models (LMM) to evaluate the effects of method, period, and sequence while accounting for the cluster-based design. Missing data will be handled via Full Information Maximum Likelihood (FIML). Mediation models will further investigate whether psycho-cognitive shifts explain the observed motor training effects. Discussion: This protocol provides a rigorous framework to evaluate how physical constraints and exposure order shape coordination. Findings will offer evidence-based recommendations for sequencing motor skill progressions in higher education, bridging theoretical motor learning and applied pedagogy.