Mental Fatigue and Performance: When the Head Quits Before the Body
Mental Fatigue and Performance: When the Head Quits Before the Body
(First-Person Consciousness • Decolonial Neuroscience • Brain Bee • The Feeling-and-Knowing Taá)
The Feeling-and-Knowing Taá — when my brain says “enough” before my muscles do
I know this feeling in my own body.
My legs are fine. My breathing is under control. If someone looked only at my muscles, they would say:
“You can keep going.”
But inside my head, something collapses.
The world feels heavier, reactions slow down, thoughts get sticky. I start negotiating with myself:
“Just stop, it’s not worth it.”
“You’re tired, you already did a lot.”
This is not pure pain. It is mental fatigue — a weight that lands on my attention, not on my quadriceps.
Taá, for me, begins exactly aqui:
the moment I feel that my mind is giving up while my body could still continue.
It is the first-person shock of noticing that “I’m not exhausted, but I can’t stand the effort of paying attention anymore.”
And in this crack between body and mind, colonization sneaks in with its language:
lazy,
weak,
lacking discipline,
not resilient enough.
The Taá of decolonizing how we name fatigue
I also notice how even my words about fatigue were colonized.
The language I inherited was trained to reduce me to a defective machine:
my body to a broken engine,
my mind to a deficit,
my spirituality to superstition,
my politics to productivity and consumption.
That is why so many neuroscientists still hesitate to ask the “forbidden” questions — the ones that might reveal how colonial science misreads exhaustion as moral failure.
But when I let my body speak before my concepts — when Taá manifests — I realize there is no separation between Neuroscience, Politics and Spirituality (Utupe, Xapiri, living memory). Mental fatigue is not just a “cognitive variable”; it is also a political and spiritual clue about how we are being used, pressed, and drained.
What colonizes is not only history; it is the vocabulary that forbids us from existing as whole beings.
Every experiment on mental fatigue, if read with courage, opens a small window out of Zone 3 (ideology, guilt, self-blame) and brings the body back to what it always was: território vivo de mundos possíveis.
The study: fNIRS, mental fatigue and endurance performance
A recent 2025 article in the Journal of Sports Sciences used functional near-infrared spectroscopy (fNIRS) over the prefrontal cortex to ask a very simple but powerful question:
How does prior mental fatigue change endurance performance and prefrontal oxygenation?
The typical paradigm looks like this:
Participants first complete a cognitively demanding task (for example, a long attention or response-inhibition task) designed to induce mental fatigue.
Then they perform a physical endurance task (such as cycling or running to exhaustion, or maintaining a fixed intensity for as long as possible).
Throughout the exercise, fNIRS sensors over the prefrontal cortex measure oxygenated (O₂Hb) and deoxygenated hemoglobin (HHb).
Performance measures include:
time to exhaustion,
perceived exertion,
changes in pacing strategy.
You can locate this line of work by searching for:
“2025 Journal of Sports Sciences mental fatigue prefrontal cortex oxygenation fNIRS endurance performance”
Methods: how they read the tired brain
Even if the sports lab is noisy and sweaty, the analysis pipeline is sophisticated. In Brain Bee language:
GLM (General Linear Model)
They model the expected hemodynamic response during exercise and compare conditions:with prior mental fatigue
vs. without prior mental fatigue.
HRF (Hemodynamic Response Function)
They assume (or estimate) how fast O₂Hb should rise and fall in the prefrontal cortex when cognitive demand increases, and check how mental fatigue distorts this HRF.Short-channels
Some optodes are placed very close together to capture superficial physiological noise (skin blood flow, scalp effects).
These short-channel signals are regressed out to isolate true cortical oxygenation.ICA / PCA
ICA (Independent Component Analysis) helps remove:
motion artifacts,
systemic oscillations,
big non-neuronal components.
PCA (Principal Component Analysis) reduces dimensionality and highlights the main patterns of oxygenation across channels and time.
Multivariate statistics
Finally, they relate:fNIRS features (O₂Hb/HHb patterns, HRF parameters),
behavioural data (performance, pacing, reaction times),
and subjective ratings (perceived exertion).
For a Brain Bee mind:
think of fNIRS here as a window on how the prefrontal cortex negotiates “keep going” versus “I’m done”.
Main findings: the invisible cost of mental fatigue
Across this line of research, one pattern keeps emerging:
Endurance performance drops after mental fatigue
Even when the muscles are physiologically capable of maintaining the effort, time to exhaustion decreases and pacing becomes more conservative.Prefrontal oxygenation patterns change
Sometimes you see higher prefrontal activation earlier in the effort, suggesting more cognitive control is needed just to maintain the same output.
In other cases, you observe a kind of prefrontal disengagement near the limit — a failure to sustain the control signal.
The limit is not purely muscular
Mental fatigue alters how the brain values and tolerates effort, not just how the body produces force.
In simple terms:
The head hits the wall before the legs do — and fNIRS can see this wall forming in the prefrontal cortex.
Reading this with our concepts
Mente Damasiana
In the Damasian mind, consciousness emerges from the dance between interoception (inside signals) and proprioception (movement and posture).
In mental fatigue:
interoception screams “I’m drained”,
while proprioception still says “we can move”.
fNIRS is catching this mismatch — a Damasian dissonance between what the brain feels and what the body could still deliver.
Eus Tensionais
Here I see at least two Eus Tensionais:
the Performance-Self: trained to push, compete, endure;
the Protector-Self: watching for overload, risk, breakdown.
Under mental fatigue, the Protector-Self gains dominance earlier, shifting the internal threshold:
“I will not pay this cognitive cost anymore.”
The study objectifies this tension as prefrontal oxygenation curves changing shape under sustained demand.
Zones 1 / 2 / 3
Zone 1 – automatic motor execution, little introspection.
Zone 2 – fruição, creative regulation, fine-tuned pacing.
Zone 3 – rigid ideologies, external pressure, guilt narratives.
In a healthy training context, good performance happens as a play between Zone 1 and Zone 2.
Mental fatigue, however, easily pushes us toward Zone 3:
“If you stop, you’re weak.”
“Pain is just weakness leaving the body.”
“No days off.”
The fNIRS paper, lido com coragem, shows that this is biologically ignorant.
Mental fatigue is not moral failure; it is a physiological ceiling on sustainable attention.
Quorum Sensing Humano (QSH)
Even in an individual protocol, there is always an invisible quorum:
the expectations of the coach,
the culture of the lab or gym,
the internalized gaze of others.
QSH here appears as the social field that demands performance “as if” mental fatigue did not exist.
The study breaks this illusion: the prefrontal cortex clearly shows that the cost is real.
DANA and the Avatares Referências
Seen through DANA, the DNA-intelligence is trying to protect the organism:
reducing drive under chronic mental overload,
preventing over-exploitation of neural resources.
If I look through my Math/Hep avatar — the avatar of energetic trade-offs — I can feel the equation:
limited glucose,
limited oxygen,
limited synaptic resources.
Mental fatigue is DANA saying: “Reorganize your life. This way of burning attention is not sustainable.”
Yãy hã mĩy (Maxakali)
Originally, Yãy hã mĩy, from the Maxakali people, refers to imitating the animal you will hunt — your body learning by becoming.
In high performance, we train by imitating our future selves: the version that finishes the race, the set, the test.
Mental fatigue shows the limit of how long I can imitate that future self without collapsing.
The fNIRS curves are a small, technical way of saying:
“This way of imitating is too expensive. We need another choreography between effort and rest.”
How this science adjusts our thinking
Before this kind of work, it was easy to call people who “quit early”:
unmotivated,
not resilient,
weak-minded.
Now we know:
mental fatigue is measurable,
prefrontal oxygenation really changes,
performance drops even when muscles are still capable.
For Latin America, with its history of overwork, precarious jobs and moralization of exhaustion, this is political:
We need laws, school schedules, work rhythms and training plans that respect cognitive load, not only muscle capacity.
Normative implications for education, sport and policy in LATAM
Schools
Stop designing days that assume infinite attention.
Use mental-fatigue evidence to justify:breaks,
varied activities,
environments that support Zone 2, not permanent Zone 3.
Sport
Training plans should see mental load as a real load, period.
Not only volume and intensity of exercise, but also:number of decisions,
tactical complexity,
cognitive pressure.
Work
Labor regulations need to include cognitive sustainability.
The brain is not a free resource.Cities
Noise, chaos, constant alerts — these are mental-fatigue machines.
Urban design is also prefrontal design.
Keywords:
“mental fatigue endurance performance prefrontal cortex oxygenation fNIRS Journal of Sports Sciences 2025”
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#Multimodal
#NIRSEEG
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#Taa
#CBDCdeVarejo
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