Heart rate variability as a strain parameter in maritime settings: a scoping review of methodological approaches to data collection and analysis in field studies on the high seas.

BACKGROUND: Seafarers are exposed to unique occupational stressors that place sustained demands on the autonomic nervous system. Heart rate variability (HRV) represents a promising non-invasive tool for assessing mental and physical strain in maritime settings. However, its methodological application in real field conditions remains poorly characterized, and existing HRV guidelines do not specifically address the methodological challenges of maritime field studies. METHODS: A scoping review was conducted following PRISMA guidelines. Eleven maritime field studies measuring HRV in operational or semi-operational settings were included and assessed for device selection, measurement quality, analysis methods, HRV metrics, and covariates. RESULTS: Chest strap systems were the most frequently used (n = 8) and showed sufficient validity for field use. Methodological heterogeneity in reporting of recording duration, analysis software, artifact handling and HRV parameters was high across studies. Operational factors including sailing schedule and work-rest organization were the most commonly examined covariates and were most frequently associated with significant HRV findings. Recurring findings were small and predominantly male populations, shared participant cohorts across multiple studies, and incomplete methodological reporting. CONCLUSION: Overall, the studies utilized HRV appropriately for their respective aims. HRV measurement in maritime field settings is feasible but methodologically demanding, and it remains an underexplored domain, which limits the conclusions that can be drawn. More detailed and standardized reporting is necessary. Based on the recurring methodological reporting gaps, this review proposes a maritime-specific reporting checklist and an overview of recommended methodological options for future studies. Larger study populations are needed to account for confounding factors on board ships.