Interactive associations of daily music engagement and nutritional behavior with psychological performance in competitive athletes: a 14-day naturalistic diary study

Background: Music engagement and nutrition are each linked to athletes' mental states, yet their combined, day-to-day influence under real training conditions remains poorly understood. Objective: To determine whether daily music engagement and nutritional behavior are independently and interactively associated with psychological performance in competitive athletes. Methods: In a 14-day naturalistic digital diary study, 180 competitive athletes (≥18 years) from university teams and sports clubs reported daily music engagement, nutritional behavior, training load, sleep quality, and psychological performance. The primary analyses used multilevel mixed-effects models to separate within-person from between-person variation and to test the music × nutrition interaction. The final reported dataset comprised 2,184 athlete-day observations from 156 athletes; the handling of excluded participants and missing records is described in the Methods. Conclusion: More favorable daily music engagement and nutritional behavior were jointly associated with greater psychological readiness. Because the design was observational and concurrent, the findings should be interpreted as within-person covariation and require confirmation in prospectively powered experimental studies.