fNIRS, Movement and Aging: How the Legs Talk to Executive Function

A BrainLatam2026 reading on frailty, prefrontal cortex, movement, Zone 2 and active aging

Before talking about aging, we need to talk about the legs.

Legs are not only structures for locomotion. They carry autonomy, rhythm, balance, circulation, confidence, territory and the possibility of continuing to participate in the world.

That is why the study “Lower-limb physical function is associated with executive function in frail older adults”, by Myles O’Brien and colleagues, published in GeroScience in 2026, is important for BrainLatam2026.

The central question can be stated as:

Is lower-limb physical function associated with executive function in older adults, especially when frailty is present?

The study evaluated 60 older adults, with an average age of 72 years, divided into a non-frail group and a very mildly frail/frail group. Physical function was assessed through tests such as the six-minute walk, 30-second sit-to-stand, handgrip strength and 8-foot up-and-go. Executive function was assessed using a computerized Stroop task, while prefrontal cortex oxygenation was measured with fNIRS.

What the study showed

The results indicate that non-frail older adults performed better in lower-limb tests such as the six-minute walk, sit-to-stand and functional mobility.

But the most important finding appears in the frailer group: better performance in the six-minute walk and sit-to-stand test was associated with faster reaction times in inhibition and cognitive switching conditions of the Stroop task.

In other words: among frailer older adults, better legs were more directly connected to executive function.

The study also found greater prefrontal oxygenation during the switching condition in non-frail participants compared with frailer participants. However, statistically adjusting for oxygenation did not eliminate the relationship between lower-limb physical function and executive function in the frailer group.

This suggests that the whole body matters. Executive function does not live isolated inside the head. It depends on bodily systems: legs, circulation, balance, strength, metabolism, respiration, autonomy and territory.

Recognition of the scientific question

The merit of the study is significant.

The researchers did not simply ask whether frail older adults have worse physical or cognitive performance. They asked whether the relationship between movement and executive function becomes especially important when the body accumulates deficits.

This is a strong question because it moves aging away from a purely brain-centered view. Instead of separating “brain” and “body,” the study shows that frailty can be understood as a systemic phenomenon.

For BrainLatam2026, this is essential: aging is not only neuronal loss. It is a reorganization of body-territory.

Equipment and limits of this reading

The abstract reports that prefrontal cortex oxygenation was measured using functional near-infrared spectroscopy — fNIRS. However, the publicly available material does not provide the brand and model of the equipment, number of channels, optode montage, source-detector distance, short channels or software used.

So this reading should be understood as based on the public abstract, not as a full methodological analysis.

Even so, the use of fNIRS is relevant because it allows researchers to observe prefrontal hemodynamic responses during an executive function task, connecting movement, frailty and cognition.

BrainLatam2026 reading

From the BrainLatam2026 perspective, the legs are part of the Damasian Mind.

Executive function is not only abstract decision-making. It emerges from a body that can stand up, walk, balance, adjust steps, occupy space and trust movement.

When the legs lose strength and endurance, the world becomes smaller. The person goes out less, explores less, meets fewer people, reduces territory, faces fewer cognitive challenges and may lose part of their metacognitive autonomy.

Here enters APUS: body-territory.

A leg that walks expands territory.
A frail leg narrows territory.
And a narrowed territory may reduce experience, bonds and cognitive updating.

Zone 1, Zone 2 and aging

In healthy aging, movement is not only exercise. It is maintenance of Zone 2.

Zone 1 appears in the task: standing up, walking, crossing, climbing, carrying, reacting.
Zone 2 appears when the person can move with enough safety to perceive, choose, coexist, learn and belong.
Zone 3 may appear when the body becomes so limited that life is organized around fear, withdrawal, dependence and loss of autonomy.

The study suggests that, in frailer older adults, preserving lower-limb function may be especially important for preserving executive function.

The practical consequence is simple: caring for the legs is also caring for the mind.

From the article’s question to a BrainLatam2026 design

The article asked:

Is lower-limb physical function associated with executive function in frail older adults?

BrainLatam2026 can expand this question:

How do movement, strength, gait, respiration, prefrontal oxygenation and territorial belonging sustain executive function in aging?

A future design could combine:

fNIRS + EEG/ERP + lower-limb EMG + ECG/HRV/RMSSD + respiration + accelerometry + gait analysis + executive tests + belonging measures.

fNIRS would assess prefrontal oxygenation during cognitive and motor tasks.
EEG/ERP could capture attention, error, inhibition and cognitive switching.
EMG would show muscle activation in the quadriceps, calf and postural muscles.
HRV/RMSSD and respiration would indicate autonomic regulation.
Accelerometry and gait analysis would show rhythm, stability and movement variability.
Belonging measures would indicate whether the person still feels able to occupy the world.

A generous decolonial critique

A decolonial critique expands the question: aging with movement does not depend only on individual biology.

It depends on sidewalks, public squares, safety, transportation, income, food, access to physical therapy, primary care, social life and a culture of care.

In Latin America, many older adults do not lose mobility only because they age. They lose it because they live in hostile cities: broken sidewalks, dangerous streets, lack of shade, poor transportation, fear, isolation and limited access to movement programs.

So the public question is:

How can we create territories where older adults continue walking, thinking, belonging and deciding?

DREX Cidadão and public policy

The connection with DREX Cidadão appears when we understand aging as social metabolism.

If older adults have minimum income, access to care, transportation, food, public space and movement programs, they preserve more autonomy. If they live in survival mode, the body closes down.

DREX Cidadão can be understood as a material basis so older adults are not trapped only in economic and territorial dependence. It can allow more time, more care, more presence and more community participation.

Movement is public policy.
Legs are bodily sovereignty.
Walking is continuing to belong.

Closing

The study by O’Brien and colleagues reminds us that executive function is not only in the brain.

It passes through the legs.
Through the step.
Through the strength to stand up.
Through the courage to go out.
Through the possibility of crossing the territory.

fNIRS helps show that the prefrontal cortex participates in this conversation, but BrainLatam2026 expands the frame: the brain ages together with the body, the city, income, family and territory.

Perhaps one of the great tasks of Decolonial Neuroscience is this: to create policies so that aging does not mean shrinking the world.

Because when the legs still talk to executive function, the person is not only walking.

They are continuing to be.

Reference

O’Brien, M. W., Ahmadi, S., Faivre, P., Quirion, I., Bouffard-Levasseur, V., Emond, T., Lang, A., MacDonald, E., Dupuy, O., Champod, A. S., Bélanger, M., & Mekari, S. (2026). Lower-limb physical function is associated with executive function in frail older adults. GeroScience. DOI: 10.1007/s11357-026-02234-7.