When Your Hormones Are Telling You To Rest: A Comparison of Conventional and Functional Syndromes
What are the similarities between Overtraining Syndrome and HPA Axis Dysfunction?
As a functional medicine provider, I often find myself explaining that we aren’t inventing new diseases—we’re simply identifying and addressing root causes before they escalate into full-blown dysfunction. At a Sports Medicine (conventional medicine CME) conference this past week, one of the topics covered was something referred to as Overtraining Syndrome (OTS) in athletes. The similarities between OTS and what we in functional medicine refer to as HPA (hypothalamus-pituitary-adrenal) axis dysfunction are undeniable. Both conditions describe the body’s struggle to recover from chronic stress, yet one is widely recognized in conventional medicine, while the other is often dismissed.
Read on for side-by-side comparison.
The Three Stages of Overtraining Syndrome
OTS occurs when the body endures excessive training without adequate recovery, leading to a breakdown in performance and overall health. It progresses in three stages that affect the autonomic system and HPA axis:
1. Functional Overreaching: This is the “pushing through” phase many athletes experience. Mild fatigue, slight decreases in performance, and subtle mood changes appear but resolve with proper rest.
2. Non-Functional Overreaching: Recovery now takes longer, and symptoms intensify. Persistent fatigue, irritability, disrupted sleep, and decreased motivation start to interfere with training and daily life. The sympathetic nervous system is dominant and hypervigilant in this stage. Patients often overall just feel 'unwell.'
3. Overtraining Syndrome: This is where things get serious. Chronic exhaustion, persistent muscle soreness, hormone imbalances, immune dysfunction, depression, and even increased injury risk become apparent. The body’s stress response is now completely dysregulated, and the parasympathetic nervous system dominates. This means excessive weight gain, brain fog - stuck in the 'rest and digest' mode.
The Connection to HPA Axis Dysfunction
In functional medicine, we recognize a nearly identical pattern in individuals exposed to prolonged stress, whether from overexercise, work, relationships, or other life demands. The hypothalamic-pituitary-adrenal (HPA) axis is responsible for regulating our stress response, primarily through cortisol production. Chronic stress—whether from overtraining or life stressors—leads to dysregulation, which progresses in much the same way as OTS.:
Acute Stress Response: Initially, the body responds with heightened cortisol production, keeping energy levels high and increasing alertness. (This is GOOD in the short term..not so good when we live in a prolonged acute stress response. In that case we progress to compensatory dysregulation in stage 2).
Compensatory Dysregulation: The system becomes overwhelmed, and cortisol patterns become erratic. Fatigue, disrupted sleep, and mood changes, like anxiety, emerge. Just as in non-functional overreaching, the sympathetic nervous system tends to be dominant and hypervigilant in this stage.
Adrenal Exhaustion (or HPA Axis Dysfunction): The body can no longer mount an appropriate stress response. Cortisol levels may plummet, leading to extreme fatigue, burnout, brain fog, hormonal imbalances, and immune suppression. Once again, in stage 3, parasympathetic output dominates the body's everyday processes and causes a significant struggle to think clearly, function effectively, and lose weight.
Functional Medicine Bridges the Gap
The medical world acknowledges Overtraining Syndrome as a real and debilitating condition, yet when similar symptoms arise in non-athletes due to chronic stress, conventional medicine often dismisses them. This is where functional medicine shines—we recognize that the body doesn’t differentiate between stress from excessive workouts and stress from an overbooked schedule.
By addressing HPA axis dysfunction early—through lifestyle adjustments, targeted nutrition, stress management, and adaptogenic herbs—we can prevent the downward spiral that leads to full-blown burnout.
The key message here is that the conventional medicine-defined Overtraining Syndrome and the functional medicine-recognized HPA axis dysfunction are just different names for the same physiological response to chronic stress. Functional medicine isn’t reinventing the wheel; we’re simply recognizing and treating these patterns before they become debilitating.
Overtraining Syndrome: A Practical Guide - PMC
A Review of Overtraining Syndrome—Recognizing the Signs and Symptoms - PMC