How do you distinguish between fatigue and overtraining? Where is the line between over-reaching and really overdoing it to the point of being destructive? We try to tease that out on this episode’s MMB…

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Table of Contents

• Overtraining Syndrome. Not very easily defined, pr …

• Jim Logan-Cancer Survivor, IM Athlete, Author

• Episode takeaways:

  • References used for the MMB

Overtraining Syndrome. Not very easily defined, prevented or treated.

Overtraining syndrome (OTS) is one of the most challenging conditions in endurance sports because it lacks a universally accepted definition, presents with highly variable symptoms, and has no single diagnostic test. While temporary fatigue after heavy training is expected and functional overreaching can even improve performance following adequate recovery, OTS represents a maladaptive response in which performance declines for weeks or months despite reduced training.

One reason OTS is difficult to define is that it exists on a continuum. Athletes routinely experience acute fatigue, functional overreaching, and occasionally non-functional overreaching, making it difficult to determine when normal training stress has progressed to a pathological state. Definitions generally rely on prolonged underperformance that cannot be explained by another medical condition, but there is no agreed-upon threshold for the duration or severity of symptoms.

Diagnosis is equally challenging because OTS is fundamentally a diagnosis of exclusion. Symptoms—including persistent fatigue, reduced exercise capacity, elevated perceived exertion, sleep disturbances, mood changes, recurrent illness, and loss of motivation—are non-specific and overlap with iron deficiency, relative energy deficiency in sport (RED-S), viral infections, endocrine disorders, depression, and other medical conditions. Although researchers have investigated biomarkers such as cortisol, testosterone, inflammatory cytokines, heart rate variability, and hormonal responses to exercise, none have demonstrated sufficient sensitivity or specificity for routine clinical use. Consequently, diagnosis depends on a thorough clinical history, exclusion of alternative causes, and careful monitoring of training load and performance.

Management is similarly complex because there is no targeted treatment. The cornerstone of therapy is reducing or temporarily stopping training while addressing contributing factors such as inadequate energy intake, poor sleep, psychological stress, illness, and insufficient recovery. Recovery timelines are highly variable; some athletes improve within several weeks, whereas others require many months before returning to their previous level of performance. Attempting to resume intense training too early often prolongs recovery.

Current research emphasizes prevention rather than treatment. Periodized training plans, adequate carbohydrate and protein intake, sufficient sleep, regular monitoring of training load and subjective wellness, and open communication between athletes, coaches, and sports medicine professionals remain the most effective strategies. Despite decades of research, OTS remains difficult to define, diagnose, and manage because it reflects the complex interaction of physiological, psychological, and environmental stressors rather than a single identifiable disease process.

In this episode’s MMB coach Juliet and I review the literature on this frustrating topic and provide some solace; this is not a major issue for the age group athlete! Thank goodness for that since the impact of OTS can be devastating and long-lasting.

Jim Logan-Cancer Survivor, IM Athlete, Author

James according to James: James J Logan, Raised in New Jersey moved to Atlanta 1993. Met and married wife Kelly in 1996, Started a home inspection business the same year. Raised one son now 21 and thriving. In April of 24 diagnosed with stage 4 terminal cancer and was given 6 months maybe 2 years to live? That was 27 months ago, currently no evidence of disease, alive and thriving. Training for the IRONMAN World Championship in October, racing for the IRONMAN Foundation, fundraising and promoting my recently published book "Just Keep TRI-ING"

James J. Logan is an endurance athlete, entrepreneur, motivational speaker, and first-time author whose memoir, Just Keep TRI-ING: The Faith-Fueled Formula to Push Through Pain, Face Your Fears, and Finish Your Race, chronicles his remarkable journey through adversity. A lifelong participant in endurance sports, Logan has completed numerous marathon and Ironman-distance events, developing a philosophy centered on discipline, perseverance, and purposeful suffering. His life changed dramatically in 2024 when he was diagnosed with stage IV metastatic colorectal cancer and given a limited prognosis. Rather than allowing the diagnosis to define him, Logan continued to train, race, and pursue ambitious goals while undergoing chemotherapy, radiation, and multiple major surgeries.

Drawing on his experiences as both an athlete and cancer patient, Logan wrote Just Keep TRI-ING to inspire readers facing challenges of all kinds. The book is more than a memoir; it presents a mindset for overcoming fear and adversity through faith, resilience, and consistent forward progress. Central to his message is the belief that success is not measured solely by finishing first or even finishing at all, but by refusing to quit when confronted with life's greatest obstacles.

Beyond sharing his personal story, Logan has dedicated the initial proceeds from his book to supporting the Ironman Foundation, reinforcing his commitment to giving back to the endurance sports community. He has also appeared on numerous endurance sports podcasts, where he discusses the physical and emotional challenges of competing while undergoing cancer treatment and emphasizes the power of maintaining hope, purpose, and perspective. Through his writing and public speaking, James Logan reminds athletes and non-athletes alike that resilience is built one decision at a time, and that even in the face of overwhelming adversity, there is strength in simply continuing to "keep TRI-ing."

My conversation with James is sure to bring a smile to your face as he is an incredibly sanguine and optimistic man who has learned the value of accepting what you have and embraces the essence of ‘anything is possible’ to the very max.

Episode takeaways:

• OTS is a frustratingly vague and difficult to diagnose and manage entity

• OTS is not a common issue for AG athletes

• Over-reaching in training is a good thing, overtraining is not. It’s the spectrum between the two that is important

• Cancer prevention is much more preferable to treatment

• Even with a cancer diagnosis, IM and triathlon in general is still a possibility

References used for the MMB

Kreher, J. B., & Schwartz, J. B. (2012). Overtraining Syndrome: A Practical Guide. Sports Health, 4(2), 128–138. (https://pmc.ncbi.nlm.nih.gov/articles/PMC3435910/)

• Article type: Narrative review / clinical guide

• Defines the continuum from functional overreaching (FOR) to non-functional overreaching (NFOR) to overtraining syndrome (OTS), with the main difference being recovery time and duration of performance decrement.

• Explains that OTS is rare and difficult to diagnose because there is no single biomarker or laboratory test, and diagnosis is made by exclusion of other conditions.

• Reviews proposed mechanisms including hormonal changes, immune dysregulation, inflammation, glycogen depletion, and autonomic nervous system changes, but notes no single mechanism fully explains OTS.

• Identifies risk factors including excessive training load, insufficient recovery, low energy availability, illness, sleep disruption, and psychological stress.

• Emphasizes that treatment requires reduction or cessation of training and gradual return once symptoms resolve.

Halson, S. L., & Jeukendrup, A. E. (2004). Does Overtraining Exist? An Analysis of Overreaching and Overtraining Research. Sports Medicine, 34(14), 967–981. (https://pubmed.ncbi.nlm.nih.gov/15571428/)

• Article type: Narrative review

• Examines whether the literature clearly distinguishes between acute fatigue, functional overreaching, non-functional overreaching, and overtraining syndrome.

• Argues that many studies labeled as OTS actually describe short-term overreaching, with recovery typically occurring within days to weeks rather than months.

• Notes that there is no reliable diagnostic test for OTS, making cross-study comparison difficult.

• Critiques the assumption that overreaching progresses linearly into overtraining, stating there is limited direct evidence supporting this model.

• Highlights inconsistencies in definitions, study design, and outcome measures across the literature.

• Concludes that the lack of standardized criteria prevents clear identification of physiological markers of OTS.

Grandou, C., Wallace, L., Impellizzeri, F. M., Allen, N. G., & Coutts, A. J. (2020). Overtraining in Resistance Exercise: An Exploratory Systematic Review and Methodological Appraisal of the Literature. Sports Medicine, 50(4), 815–828. (https://pubmed.ncbi.nlm.nih.gov/31820373/)

• Article type: Systematic review and methodological appraisal

• Reviews resistance training studies attempting to induce functional overreaching, non-functional overreaching, or overtraining syndrome.

• Finds substantial heterogeneity in study design, definitions, and outcome measures.

• Notes that many studies lack standardized criteria for diagnosing overtraining and often rely on short-term performance changes.

• Reports that sustained performance impairment, a key feature of OTS, is rarely clearly demonstrated.

• Highlights difficulty distinguishing training-induced fatigue from true overtraining in resistance exercise research.

• Concludes that no single marker reliably identifies overtraining in resistance training contexts.

Armstrong, L. E., & VanHeest, J. L. (2022). The Unknown Mechanism of Overtraining Syndrome: Clues from Depression and Heat Illness. Sports Medicine, 52(3), 463–486. (https://pmc.ncbi.nlm.nih.gov/articles/PMC9724109/)

• Article type: Narrative review

• Reviews overtraining syndrome as a condition without a clearly defined biological mechanism.

• Emphasizes that OTS is defined primarily by prolonged performance decline that does not resolve with rest.

• Compares OTS to depression and exertional heat illness, suggesting possible shared stress-response pathways.

• Discusses potential involvement of central nervous system regulation, autonomic nervous system function, and neuroendocrine signaling.

• Notes that proposed physiological markers are inconsistent and not diagnostically reliable.

• Highlights the challenge of distinguishing OTS from related conditions such as illness, psychological disorders, and energy deficiency states.

Fiala, O., Hanzlova, M., Borska, L., Fiala, Z., & Holmannova, D. (2025). Beyond Physical Exhaustion: Understanding Overtraining Syndrome Through the Lens of Molecular Mechanisms and Clinical Manifestation. Sports Medicine and Health Science. (https://pubmed.ncbi.nlm.nih.gov/40264836/)

• Article type: Narrative review

• Reviews proposed mechanisms of OTS including inflammation, oxidative stress, immune dysregulation, endocrine disruption (HPA axis), autonomic nervous system imbalance, and energy depletion.

• Describes OTS as a multisystem condition affecting not only skeletal muscle but also immune, endocrine, cardiovascular, nervous, and metabolic systems.

• Notes that chronic low-grade inflammation and altered cytokine signaling have been observed in some cases, but findings are inconsistent.

• Discusses gut microbiome disruption as an emerging but still preliminary area of research.

• Emphasizes that no single biological mechanism explains all cases of OTS.

• Reinforces that OTS results from imbalance between training load and recovery, with sleep, nutrition, and psychological stress as contributing factors.

Stellingwerff, T., Heikura, I. A., Meeusen, R., Bermon, S., Seiler, S., Mountjoy, M. L., & Burke, L. M. (2021). Overtraining Syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S): Shared Pathways, Symptoms and Complexities. Sports Medicine, 51(11), 2251–2280. (https://pubmed.ncbi.nlm.nih.gov/34181189/)

• Article type: Narrative review

• Compares overtraining syndrome (OTS) and Relative Energy Deficiency in Sport (RED-S), emphasizing overlapping symptoms including fatigue, performance decline, hormonal disruption, and mood changes.

• Argues that many cases attributed to OTS may actually reflect low energy availability rather than training load alone.

• Highlights that experimental overtraining studies often include reductions in energy intake or carbohydrate availability.

• Describes shared disruption of the hypothalamic-pituitary axis affecting endocrine and metabolic function.

• Notes that OTS and RED-S are difficult to distinguish clinically due to overlapping presentations.

• Emphasizes lack of clear diagnostic criteria separating the two conditions.

Cabre, H. E., & Moore, S. R. (2022). Relative Energy Deficiency in Sport (RED-S): Scientific, Clinical, and Practical Implications for the Female Athlete. Deutsche Zeitschrift für Sportmedizin. (https://pmc.ncbi.nlm.nih.gov/articles/PMC9724109/)

• Article type: Narrative review

• Describes Relative Energy Deficiency in Sport (RED-S) as a condition caused by low energy availability (LEA), where energy intake is insufficient to support the demands of exercise and basic physiological function.

• Expands on the earlier Female Athlete Triad model by emphasizing that the effects of LEA extend beyond reproductive and bone health to include metabolic, cardiovascular, gastrointestinal, immune, and psychological systems.

• Defines LEA thresholds and notes that chronic or repeated periods of insufficient energy availability can impair training adaptation, performance, and overall health.

• Highlights that RED-S can present with a wide range of symptoms, including menstrual dysfunction, fatigue, frequent illness, stress fractures, and mood changes, but that presentation is often variable and under-recognized.

• Emphasizes that both prevention and treatment depend heavily on restoring adequate energy availability through nutrition, rather than only modifying training load.

• Notes that screening is challenging because athletes may not present with obvious weight loss or disordered eating behaviors, and diagnosis often requires a combination of clinical history, symptoms, and risk assessment tools (e.g., RED-S CAT).

Kreher, J. B., Stepanek, J., Amrine, R., & Reddy, S. (2025). Overtraining Syndrome (OTS) in Three Endurance Athletes and Roads to Recovery. BMJ Case Reports. (https://pmc.ncbi.nlm.nih.gov/articles/PMC12258013/)

• Article type: Case series (3 endurance athletes: professional, competitive, recreational)

• Describes three endurance athletes diagnosed with overtraining syndrome (OTS), each presenting with persistent performance decline, fatigue, and multisystem symptoms despite continued or reduced training.

• Highlights that symptom presentation varied across athletes but commonly included prolonged fatigue, impaired recovery, mood changes, sleep disturbance, and loss of performance capacity.

• Emphasizes that diagnosis was clinical and required exclusion of other conditions, including medical illness, endocrine disorders, and relative energy deficiency in sport (RED-S).

• Notes that all three cases involved a period of training stress combined with insufficient recovery and/or fueling challenges, though the relative contribution of each factor varied by athlete.

• Describes recovery as gradual and highly individualized, requiring prolonged reductions in training load, structured return-to-training protocols, and attention to sleep and nutrition.

• Highlights the importance of multidisciplinary management, including sports medicine, nutrition, and physical therapy input.

• Reinforces that OTS is difficult to define and diagnose because there is no objective biomarker and symptoms overlap with RED-S, burnout, and other chronic fatigue states.