Kurt Rowley Health Systems | ME/CFS · Systems Theory
The standard medical advice for ME/CFS — rest when you feel bad, push when you feel better — fails most patients who follow it. Not because the advice is poorly intentioned, but because it applies a linear model to a nonlinear system.
The Linear Model and Why It Fails
In a linear system, output is proportional to input. Rest more → recover more. Push harder → accomplish more. The problem is that ME/CFS doesn't behave this way. It exhibits what systems scientists call post-exertional malaise (PEM): a delayed, disproportionate worsening of symptoms triggered by exertion that was tolerable at the time.
This is a signature of a nonlinear feedback system with threshold behavior. The system appears stable until a threshold is crossed, then collapses into a lower-energy attractor state — what patients describe as a "crash."
The Energy Envelope as a Systems Concept
The concept of the energy envelope — staying within your available energy supply rather than drawing against future reserves — is intuitively correct and systems-theoretically grounded.
Think of it as a stock-and-flow model:
- Stock: Available cellular energy (roughly, mitochondrial output capacity)
- Inflows: Rest, sleep, nutrition, reduced sympathetic load
- Outflows: Physical exertion, cognitive exertion, emotional stress, immune activation
- Threshold: The level below which the system tips into a crash state
The key insight is that the threshold itself fluctuates. It is not fixed. It is set by the current state of the dysregulated system, which includes inflammation levels, autonomic tone, sleep quality, and accumulated exertion history.
Why Rest Alone Doesn't Work
Pure rest fails for two reasons:
1. It doesn't address the underlying feedback dysregulation. The system isn't simply depleted — it's dysregulated. The control loops that normally govern energy allocation, immune response, and autonomic tone are sending incorrect signals. Rest reduces outflows but doesn't repair the control architecture.
2. Deconditioning creates a secondary problem. Prolonged inactivity causes mitochondrial downregulation, muscle atrophy, and autonomic deconditioning — all of which reduce the threshold. The system becomes increasingly fragile even as the patient rests.
What the Feedback Dynamics Suggest
A systems-informed approach does three things:
- Stabilizes the envelope — neither pushing into threshold territory nor falling into deconditioning.
- Targets the control loops — interventions that address autonomic dysregulation, inflammation signaling, and cellular energy production rather than just symptom management.
- Works with delay, not against it — recognizing that feedback in this system is delayed. How you feel now does not predict how you will feel tomorrow after today's exertion.
Breathing interventions, pacing protocols, and nervous system regulation techniques all work, at least in part, because they operate on the control architecture of the system rather than just the energy stock.
This note is part of an evolving series on the systems theory of ME/CFS. See also: Health Systems.