Integrated Monitoring of Hepcidin, Inflammatory Markers and Heart Rate Variability in Endurance Athletes: Implications for Early Detection of Non-Functional Overreaching - A Narrative Review
DOI:
https://doi.org/10.12775/QS.2026.60.72789Keywords
non-functional overreaching, overtraining syndrome, endurance athletes, hepcidin, inflammation, interleukin-6, heart rate variability, iron metabolismAbstract
Background
Non-functional overreaching (NFOR) and overtraining syndrome (OTS) are maladaptive responses to excessive training load combined with insufficient recovery. Early diagnosis remains difficult because no single validated biomarker can reliably distinguish physiological fatigue from clinically significant maladaptation. Endurance athletes appear particularly vulnerable due to repeated exposure to high training volume, inflammatory activation and disturbances in iron metabolism.
Objective
The aim of this review was to evaluate the role of hepcidin, inflammatory markers and heart rate variability (HRV) as potential early indicators of non-functional overreaching in endurance athletes and to discuss the clinical relevance of integrated monitoring strategies.
Methods
A narrative review with systematic search elements was performed using PubMed/MEDLINE and scientific databases. The review included systematic reviews, meta-analyses, consensus statements and original studies published primarily between 2019 and 2026 focusing on endurance athletes, HRV, inflammation and iron metabolism.
Results
Available evidence suggests that HRV, particularly RMSSD, may reflect autonomic adaptation and recovery status during intensified training periods. Exercise-induced inflammatory activation, especially increased interleukin-6, contributes to post-exercise elevation of hepcidin, potentially reducing iron availability and impairing recovery capacity. However, HRV and inflammatory biomarkers are influenced by multiple physiological and environmental factors, limiting their isolated diagnostic value.
Conclusions
An integrated approach combining HRV trends, inflammatory markers and iron-regulatory biomarkers may improve early identification of athletes at risk of non-functional overreaching. Further prospective studies are required to validate combined monitoring strategies in endurance athletes.
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Copyright (c) 2026 Magdalena Kolasa, Natalia Kasterka, Liwia Karbownik, Agnieszka Figwer, Krzysztof Figwer, Kinga Dzitkowska, Norbert Czarny, Anna Broniecka, Michał Śmigielski, Jędrzej Garbaciak
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