Recovery fatigue: stop attributing it to age

The system that was supposed to extinguish inflammation and why it is gradually losing its effectiveness

Nicolas knows this path by heart.

He did it for the first time at thirty-eight, with his sons, on a Saturday in November. They had left early, before the fog lifted over the valley. He remembers walking quickly, waiting for them at the top, and sitting on a rock with a thermos of coffee.

This morning, he sets off alone on this path again.

Halfway through, he stops. He is not out of breath, but his legs feel different than before, at this precise point on the path where he had never needed to stop.

He sets off again calmly and reaches the top.

Sitting on the same rock, he gazes down at the valley below and tries to remember how long he has been like this.

He can't find a precise answer. In fact, he has no idea at all.

Nicolas is not sick.

If he were given a blood test tomorrow morning, the results would likely be back within normal limits. There's no marker that would explain what he's feeling on this trail.

He eats adequately overall and sleeps well.

But lately, something has changed in the way his body recovers after exertion or a busy period. Before, he would recover. Not quickly, not easily, but he would recover. Now, the next morning doesn't start quite from the same point as the day before. He couldn't explain why. It happened too gradually for him to notice.

Many people are familiar with this condition but cannot name it.

Not serious enough to warrant a consultation, but noticeable nonetheless. The days go by, he lays his tiles as usual. But in the evening, he no longer has the energy he used to. As if his margin for error had shrunk.

One might think that age explains everything. That it's normal to recover less quickly after forty. That's true, in part.

But age alone isn't enough to explain what Nicolas feels on this trail. Nor is it enough to explain why some sixty-year-olds recover better than forty-five-year-olds. There's a more precise mechanism at work, one that has been operating for years, which explains why the body gradually loses its ability to return to equilibrium.

This mechanism is not the inflammation itself. It is the system that was supposed to extinguish it.

The body has several systems to contain and then resolve inflammation. One of the most important involves cortisol.

It is an active, precise mechanism that mobilizes specific resources to put an end to what it itself triggered.

Produced by the adrenal glands on the brain's orders, via a regulatory pathway called the HPA axis (hypothalamic-pituitary-adrenal axis), cortisol is essentially a powerful natural anti-inflammatory. When inflammation occurs, it intervenes to modulate it, prevent it from spiraling out of control, and allow the body to return to equilibrium. Without it, even the slightest immune response would risk becoming excessively inflamed.

For years, this mechanism worked well for Nicolas. A period of stress, an infection: cortisol would rise, extinguish the inflammatory response, and Nicolas would recover.

But when stress persists, when the HPA axis remains under stress for months, years, something gradually changes.

Immune cells, constantly exposed to chronically elevated cortisol, gradually cease to respond to its signal. They become accustomed to it and respond less and less to its instructions. The anti-inflammatory effect that cortisol was supposed to exert becomes less effective, much like in insulin resistance: the signal is still there, but it is less clearly understood.

This is the first phase. Corti