Abstract
This systematic literature review synthesised evidence on digital biomarkers relevant to psychological and autonomic readiness in volleyball, with particular attention to beach-volleyball contexts. The review followed PRISMA 2020 and used a structured Scopus search covering wearable sensors, heart-rate variability (HRV), autonomic regulation, well-being, recovery, monitoring, training load, and fatigue. The search identified 186 records; 45 full texts were assessed and 10 records were retained for the qualitative evidence map, including empirical studies and two secondary syntheses used for contextual benchmarking. Three themes were identified: autonomic regulation, wearable and inertial kinetics, and ecological psychological monitoring. HRV was sensitive to training and competition load, wearable measures characterized external and neuromuscular demands, and repeated self-report and sleep measures provided ecologically situated information about perceived readiness. However, the included studies did not establish construct equivalence for a single latent readiness variable, and direct multimodal criterion validation against performance outcomes was uncommon. Because independent screening logs and item-level appraisal sheets were not preserved in the source file, inter-rater agreement and retrospective risk-of-bias scores could not be reconstructed without introducing unverifiable data. The synthesis therefore emphasizes descriptive convergence and methodological heterogeneity rather than a pooled effect estimate. Future research should preregister readiness operationalizations, standardize HRV and ecological sampling protocols, synchronize psychological and wearable streams, and validate multimodal models prospectively in beach-volleyball environments.