Before every time trial I can remember, I did the same thing.
Deep, fast breaths in the final minutes before the start. Big inhales, filling the lungs, loading the blood with oxygen. Every rider around me was doing the same. The coaches encouraged it. The logic seemed obvious: more oxygen in the blood means more energy, more watts, better result.
I did this for fifteen years.
I was wrong. And so was almost everyone around me.
What I was actually doing with those deep, rapid breaths was flushing CO₂ out of my blood faster than my body could replace it. The blood was already full. What changed was where it could go: with CO₂ that low, the vessels in the brain and in the working muscle narrow, and the engine starts slower, on the wrong fuel.
The assumption most athletes never question
The assumption is simple: breathe more, get more oxygen, perform better.
The chemistry does not work that way.
Oxygen is already abundant in your blood during normal breathing. Your blood is roughly 95–99% saturated with oxygen under resting conditions. Breathing more does not meaningfully increase that saturation. What it does do is change CO₂ levels.
And CO₂ is not the waste gas we were taught to expel as quickly as possible. It is a regulator. It keeps blood vessels open, it sets the drive to breathe, and together with the acid a working muscle makes, it helps hemoglobin release oxygen where the work is. That last part is called the Bohr effect. It is real, and it is the smaller part of the story: the release happens mostly inside the muscle, from what the muscle itself produces. The larger part is what low CO₂ does to blood flow and to the brain.
Normal CO₂. Vessels in the brain and the working muscle stay open. The engine starts on time, and the muscle's own acid makes hemoglobin let go where the work is. Energy follows breath.
Fig. 01 — What Over-Breathing Does
When you hyperventilate, even briefly and intentionally, you flush CO₂ out faster than the body replaces it. Three things follow. The vessels in the brain narrow, and with them the brain's drive to the muscle. The vessels in the working muscle narrow too, so the first minutes of effort start on less blood and the oxygen uptake settles more slowly. And the muscle leans on its quick, acid-making fuel sooner. The oxygen is there. The road to the muscle got narrower, and the engine started late. The blood is full, and you get less out of it.
For fifteen years I was preparing for time trials by narrowing the road to my own legs and quieting my own brain. And feeling like I was doing something smart.
The spiral that creates anxiety
The same mechanism that sabotages a time trial warm-up creates anxiety before competition.
When breathing becomes fast and shallow under pressure, CO₂ drops. The brain's chemoreceptors detect the shift and read it as threat. Not because something external is dangerous. Because the internal chemistry now resembles the chemistry of actual danger.
The brain responds by increasing arousal. Heart rate rises. Attention narrows. The urge to breathe more intensifies. Which drops CO₂ further. Which increases the threat signal. Which drives faster breathing still.
Tap a node. Each step accelerates the next. The mind is a passenger; the chemistry drives.
Fig. 02 — The Anxiety Spiral
The anxiety spiral is not primarily a thought pattern. It is a chemistry loop, read by a brain that does not measure the chemistry directly. What you feel is the brain comparing what it asked the breathing muscles to do with what came back, and adding its own judgment about whether the gap is dangerous. Two athletes at the same CO₂ can feel completely different alarm. That judgment is trainable, and it is why the athlete trying to calm down by taking bigger breaths is often accelerating the exact cycle they are trying to stop.
This is why "just breathe" can make things worse. A fast, deep inhale into the chest drops CO₂ more rapidly than a controlled exhale can restore it. The intention is correct. The mechanics are working against it.
The chest is your body's emergency signal
There is a second problem that runs in parallel.
When the diaphragm is restricted, breathing moves into the chest. The neck and shoulder muscles take over. The upper body tightens and elevates slightly.
This is how the body breathes when something is genuinely dangerous.
Emergency signal. Neck and chest do the work the diaphragm should. The brain reads the posture as: something is wrong — even when nothing is.
Fig. 03 — Chest vs. Belly Breathing
Chest-dominant breathing with elevated shoulders and a tight neck is the physical signature of the threat response. When the nervous system detects this pattern from inside the body, it does not ask whether the cause is real or not. It reads the posture and responds accordingly. The physical state of emergency breathing produces the neurological signal of emergency, regardless of what is actually happening in the outside world.
This is the exact mechanism that made my pre-race hyperventilation counterproductive on two levels at once. The rapid inhales were dropping CO₂ and reducing oxygen delivery to working muscle. And the chest-dominant pattern was sending my nervous system into a low-grade threat state right before the start gun.
I thought I was preparing. I was activating an alarm.
Why breath restriction is sometimes a strategy, not a mistake
There is a third layer that explains why "just breathe" fails so often for athletes under real pressure.
Breathing creates feeling.
Alexander LowenA full, unrestricted breath amplifies sensation. Emotion becomes more present. And for athletes who have spent years learning to suppress what they feel in order to compete, a full breath can feel threatening. Not because breathing is dangerous. Because what it might surface is something the system has been keeping below the threshold where it interferes with function.
The athlete who goes shallow before a race is often not forgetting to breathe. They are doing something specific: reducing sensation to stay in control. Holding the volume low enough that fear, doubt, or emotion does not break through at the wrong moment.
This is a strategy. It has a cost. But it has a logic.
Which is why instruction alone rarely fixes it. The restriction exists because the system created it for a reason. Telling it to simply open up does not address that reason.
What actually changes it
The entry point is not a better breathing technique. It is a slower, softer exhale.
Not a bigger inhale. The exhale. Specifically, one that is longer than the inhale, initiated from the belly rather than the chest, and allowed to complete fully before the next breath begins.
The slow exhale is the entry point. Longer than the inhale. Initiated from the belly. Allowed to complete fully. CO₂ rises slightly, smooth muscle relaxes, the autonomic nervous system receives the signal: safe.
Fig. 04 — Inhale vs. Exhale Ratio
A slow exhale raises CO₂ slightly. Raised CO₂ relaxes smooth muscle, reduces accessory muscle tension, and signals the autonomic nervous system toward safety. It is the one part of breathing that most directly activates the parasympathetic system, and it is the one part that chest-dominant hyperventilation systematically skips.
One long exhale will not undo fifteen years of pre-race ritual. But it will shift the chemistry slightly. Drop the chest tension slightly. Give the nervous system one signal that contradicts the alarm it was building.
And unlike a forced deep inhale, it will not make things worse.
That is the starting point. Not perfecting the breath. Building enough trust in the exhale that the system is willing to let the next one come naturally.
Next week
The right thought only works in the right state. Why mental performance tools work in training and break down at the moments they are needed most — and what that tells you about where the real work actually happens.
JB Method — Reliable Under Pressure