Overtraining and Nervous System Dysfunction: The Link to Chronic Illness
- FND Health
- Apr 6
- 6 min read
"I used to squat 500 pounds and train six days a week. Now taking a shower wipes me out and makes me feel like I’m about to die." — GC, @ThePOTSPostman on X
This kind of story is becoming all too common. People who once pushed their bodies to the limit—whether in weightlifting, endurance sports, or high-intensity training—suddenly find themselves unable to function. They go from peak fitness to chronic fatigue, experiencing symptoms like post-exertional crashes, unrefreshing sleep, tremors, and a nervous system that feels completely out of control.
But why does this happen? Why do some athletes seem to recover effortlessly, while others end up with conditions like ME/CFS, fibromyalgia, POTS or FND? The answer might lie in the nervous system itself—specifically, in how some people are wired.
A Nervous System That Never Fully Switches Off
I used to be one of those people who was always active, always pushing myself to the limit. My strength wasn’t just physical—it was mental, too. The ability to keep going, to push through exhaustion, was something I prided myself on. Yet, in hindsight, I see the signs were always there: difficulty winding down, restless sleep, and a constant feeling of being "wired," even when I was physically exhausted.
For many of us with conditions like ME/CFS, POTS, or fibromyalgia, these signs of dysregulation were present long before we hit a breaking point. The body may have kept up for a while, but eventually, the nervous system couldn’t compensate anymore, and that’s when everything changed.
Signs Your Nervous System May Be Struggling to Switch Between States:
For many of us who develop chronic nervous system dysfunction, the warning signs were there long before the full crash. A common pattern emerges:
Difficulty winding down after intense activity – Instead of feeling tired after a long day of training, we feel wired. While others can rest, we stay alert, buzzing with energy, unable to switch off.
Restless sleep and night-time overstimulation – Even when exhausted, our body doesn’t fully relax. We might wake up frequently, experience vivid dreams or nightmares, or struggle with insomnia.
Sensitivity to stress and overstimulation – Loud noises, bright lights, or even minor stressors feel overwhelming, triggering an exaggerated nervous system response.
A history of pushing through – We train harder, work longer, and ignore the signs of burnout because rest never feels truly restful. Instead of recharging, we feel agitated, restless, or mentally exhausted.
This suggests that, for some of us, our autonomic nervous system (ANS) has always been slightly dysregulated. The ability to shift from fight-or-flight (sympathetic) to rest-and-digest (parasympathetic) is impaired. Instead of smoothly transitioning between these states, our nervous system lingers in high alert, making it harder for us to recover from stress.
Overtraining and the Breaking Point
Over time, relentless physical stress—whether from intense workouts, chronic stress, or even illness—can overwhelm the nervous system. If someone already has a predisposition toward autonomic dysfunction, the cumulative effect of overtraining, lack of proper recovery, and life stress can eventually push them into a full-blown breakdown.
This could explain why some athletes develop conditions like ME/CFS, POTS, or fibromyalgia after years of intense training:
Chronic Sympathetic Activation – Too much time in fight-or-flight mode can lead to dysautonomia, where the nervous system loses its ability to regulate itself properly.
Neuroinflammation and Immune Dysfunction – A constantly activated nervous system can lead to systemic inflammation, making the body more vulnerable to viral reactivations, immune dysregulation, and long-term fatigue.
HPA Axis Dysfunction – The stress response system (hypothalamus-pituitary-adrenal axis) can become blunted, leading to symptoms like low cortisol, poor stress tolerance, and crashes after minimal exertion.
At some point, the body hits a wall. What once felt like pushing through fatigue becomes a complete inability to function. The nervous system, no longer able to compensate, becomes hypersensitive—overreacting to physical exertion, stress, and even basic sensory input.
Healing a Nervous System That Won't Switch Off
Recovering from this kind of breakdown isn’t as simple as resting. If the core issue is a nervous system that never fully relaxes, then true healing requires retraining it to properly shift into parasympathetic mode.
1. Rebuilding the Parasympathetic Response
Techniques like breathwork, and progressive relaxation can help signal to the body that it’s safe to shut down. The goal isn’t just to "rest," but to actively train the nervous system to transition out of high-alert mode.
2. Pacing and Nervous System Regulation
Instead of pushing through or fully resting, finding the right balance of gentle movement and structured recovery is key. Overdoing it can worsen symptoms, but avoiding all activity can lead to further dysregulation. The key is learning to listen to the nervous system and work within its limits.
3. Reducing Overstimulation
For someone whose nervous system is hypersensitive, even minor stimuli like bright lights, loud sounds, or stressful conversations can be exhausting. Reducing these inputs—especially in the early stages of recovery—can prevent unnecessary nervous system activation.
4. Diet and Gut-Brain Connection
The nervous system and gut are deeply linked. Anti-inflammatory foods, gut-healing protocols, and avoiding stimulants (like caffeine or sugar) can help reduce nervous system hypersensitivity. Probiotics, prebiotics, and a nutrient-dense diet may support nervous system recovery.
5. Rewiring the Brain’s Perception of Safety
Neuroplasticity-based approaches (like brain retraining programs) can help shift the nervous system out of a chronic stress response. If the body has been stuck in survival mode for years, it may need to learn that it’s safe to rest and heal.
The Path Forward
If you’ve experienced this kind of nervous system breakdown, you’re not alone. Many people who were once highly active find themselves trapped in a body that no longer functions the way it used to. The frustration of losing physical strength and independence is real—but so is the possibility of improvement.
Healing isn’t about pushing harder. It’s about retraining the nervous system to find balance again, teaching it to shift out of survival mode and into a state where true healing can happen. The nervous system isn’t broken—it’s just stuck. And with the right approach, it can be rewired.
However, it’s important to remember that the nervous system, especially if it’s been this way for years or even since birth, will need ongoing care. Improving its function is a continuous process, requiring attention to diet, rest, stress management, and pacing. You don’t need to force your way through the discomfort—you need to support your system so it can heal at its own pace.
References
Dysregulation of the Autonomic Nervous System in ME/CFS and Post-COVID Syndrome: This study investigates autonomic nervous system (ANS) dysregulation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and Post-COVID Syndrome, highlighting similarities in ANS dysfunction between the conditions. Journal of the Neurological Sciences+1PMC+1
Overtraining Syndrome: A Practical Guide: This guide discusses how overtraining without adequate rest can lead to maladaptive responses affecting multiple body systems, including neurologic, endocrinologic, and immunologic systems. PMC
Effects of Exercise Training on the Autonomic Nervous System with a Focus on the Central Components: This article explores how chronic inflammation increases sympathetic nervous system (SNS) and hypothalamic-pituitary-adrenal (HPA) axis activity, potentially leading to immune suppression and other adverse effects. PMC
Breathing Practices for Stress and Anxiety Reduction: This research indicates that effective breathing interventions can enhance parasympathetic tone, counterbalancing high sympathetic activity associated with stress and anxiety. PMC
The Role of Probiotics and Prebiotics in Modulating the Gut-Brain Axis: This review discusses how probiotics and prebiotics can influence the gut-brain axis, supporting central nervous system function and potentially alleviating mental health disorders. EatingWell+7PMC+7ScienceDirect+7
Neuroplasticity Intervention, Amygdala and Insula Retraining (AIR) for Post-COVID Conditions: This study highlights the use of neuroplasticity techniques to develop new neural pathways that signal safety to the brain and body, aiding in recovery from chronic conditions. PMC
The Brain-Gut Connection: This article from Johns Hopkins Medicine explains the complex interactions between the digestive system and the brain, emphasizing the impact of gut health on mood and overall well-being. Home
Overtraining Syndrome as a Complex Systems Phenomenon: This research discusses the role of the HPA and sympathetic-adrenal-medullary (SAM) axes in responding to life stresses and their involvement in overtraining syndrome. Frontiers
Overtraining Syndrome - Physiopedia: This resource outlines how an imbalance between exercise stress load, life stress, and rest can lead to overtraining syndrome, emphasizing the importance of preventative management. Physiopedia
The Potential Role of Nutrition in Overtraining Syndrome: This article explores how systemic inflammation and its effects on the central nervous system, including neurohormonal changes, can contribute to overtraining syndrome. MDPI
Kommentare