Exploring Autonomic Dysfunction in Overtraining: An Updated Narrative Review

Background: Overtraining syndrome (OTS) is a maladaptive response to prolonged training stress with insufficient recovery, leading to persistent performance decline and physiological dysfunction. Despite its recognition in sport and clinical contexts, the precise mechanisms underlying OTS remain poorly understood, researched, and diagnosis is often reliant on subjective clinical judgment. Purpose: This narrative review explores the autonomic imbalance hypothesis as a potential framework for understanding the physiological basis of OTS, emphasizing its relevance to cardiovascular, neuroendocrine, and gastrointestinal dysregulation. Methods: A non-systematic, narrative approach was used to conceptualize foundational literature on the topic. Targeted searches of PubMed and Google Scholar were conducted using keywords such as “overtraining syndrome”, “autonomic nervous system”, “autonomic nervous system regulation”, and “parasympathetic dominance”. Articles were selected based on their relevance to the autonomic regulation mechanisms implicated in OTS. Results: The literature supports the benefit of further investigation into the autonomic imbalance hypothesis and how it may provide a potential framework for mechanisms underlying the progression of OTS. Central mechanisms involving baroreceptor and chemoreceptor sensitivity, hypothalamic regulation, adrenal function, and gut-brain axis disruptions are highlighted as possible contributors to the syndrome’s clinical manifestations. Conclusion: The autonomic imbalance hypothesis provides a promising lens through which to understand the physiological complexity of OTS. However, empirical validation remains limited. Future research is desperately needed to clarify causal mechanisms, refine diagnostic tools, and assess implications for youth athletes.