Is Better Diet Quality Linked to Better Competitive Functioning? An Integrative Multi-Analytic Study of Sleep Difficulty and Subjective Vitality Among Chinese Collegiate Athletes.

Higher diet quality was significantly associated with fewer sleep difficulties and with higher subjective vitality, self-rated physical fitness, and competitive psychological readiness.

• Cross-sectional survey of 1641 collegiate athletes in provincial-level university sporting events in Yunnan and Guizhou, China.
• Assessments were completed on the athletes' competition check-in day.
• All core variables were self-reported; competitive psychological readiness was operationalized as mental toughness.

Significant cross-sectional indirect associations between diet quality and both outcomes were found via sleep difficulty alone, subjective vitality alone, and the ordered sleep difficulty–subjective vitality term.

• Estimated using PROCESS Model 6 (serial mediation framework).
• Indirect associations were significant in both the self-rated physical fitness and the competitive psychological readiness models.
• The subjective-vitality-only indirect estimate was the largest.

Network analysis showed that sleep-difficulty nodes had predominantly negative bridging connections, whereas subjective-vitality nodes had primarily positive bridging connections across communities.

• Regularized partial-correlation networks and bridge centrality analyses were used to characterize item-level conditional associations.
• Bridging was assessed across communities of items (e.g., diet, sleep, vitality, outcomes).

Ridge regression showed moderate out-of-sample predictive performance for both outcomes.

• Holdout R2 was 0.415 for self-rated physical fitness.
• Holdout R2 was 0.341 for competitive psychological readiness.

In exploratory XGBoost models, subjective vitality had the highest relative SHAP importance for both outcomes.

• SHAP values quantified relative predictive contribution of variables within the XGBoost models.
• This pattern was observed in both the physical fitness and psychological readiness models.
• Analyses were described as exploratory.

The authors conclude the findings support considering nutrition, sleep, and daytime vitality within an integrated athlete-support framework, while noting that causal and temporal claims cannot be made.

• Design is cross-sectional with self-report measures.
• Temporal ordering and effects of modifying these factors require longitudinal and experimental testing.