How the ATNR Reflex Affects Swimming and Writing: Understanding the Brain-Body Connection

The ATNR, or Asymmetrical Tonic Neck Reflex, links the movement of the head with the arms and legs. If it remains active beyond infancy, it can affect coordination, swimming rhythm, and written expression. Integrating this reflex through neurodevelopmental therapy helps the brain coordinate both sides of the body for smooth movement and clear thinking.

“How Do I Know You Struggle with Swimming and Writing? Am I a Mind Reader?”

Parents often ask this when I mention the ATNR reflex. It can seem uncanny , but the patterns are predictable once you understand how the brain and body develop.When I see a child who struggles to keep a steady freestyle stroke, breathing and keeping those legs kicking takes an incredible amount of coordination. Or if they becomes frustrated trying to get their thoughts onto paper, I often suspect that the Asymmetrical Tonic Neck Reflex (ATNR) is still active.

What Is the ATNR Reflex?

The ATNR reflex develops in the womb and helps the baby with early movement and birth. When the baby turns their head to one side, the arm and leg on that side extend while the opposite side bends. This reflex helps a newborn begin to understand left and right and prepares the brain for future skills like rolling and crawling.

By six months of age, this reflex should integrate, meaning the brain no longer triggers it automatically. When it doesn’t, it can continue to interfere with coordinated movement and the ability to cross the midline (the invisible line that divides the body into left and right sides).

The ATNR and Swimming Coordination

Freestyle swimming requires both sides of the body to work together and separately while the head turns rhythmically for breathing. If the ATNR is still active, each head turn can trigger that automatic pattern, one arm straightening while the other bends, throwing off rhythm, balance, and endurance. When this is a struggle you can often see swimming teachers taking the child’s arm and guiding it out of the water to show them how to do the stroke with a straight arm instead of a bent arm.

Children (and adults) with a retained ATNR often:

• Struggle to keep a consistent stroke pattern

• Find bilateral coordination tiring or confusing

• Overuse one side of the body

• Feel unbalanced when turning the head to breathe

• Show frustration or fatigue quickly in swimming lessons
  

Instead of the smooth, alternating motion freestyle requires, their brain is constantly fighting an old reflex pattern that was meant to switch off years ago.

The ATNR and Written Expression

Writing relies on the same cross-body coordination. To write comfortably, the eyes, hands, and shoulders must work together while the head remains still and focused on the page. At the same time, sitting still, blocking out background noise and remembering what they were asked to write. A retained ATNR makes this difficult. Turning the head slightly to look across the page can cause one arm to extend and the other to bend, affecting pencil control and posture. This is subtle and you will only notice the struggle rather than the pattern of movement. Sometimes you will see the child or adult resting their head on the supporting hand to help maintain posture and moving the page to the side of the writing hand, rather than right in front of them.

Common signs in the classroom include:

• Poor handwriting or inconsistent letter size

• Fatigue when writing

• Head movement instead of eye tracking across the page

• Difficulty copying from the board

• Trouble transferring ideas into written sentences

• Missing words or unfinished sentences

  
  

The result is often a child who can say amazing things but struggles to write them down. Their brain is busy managing motor control instead of freely expressing ideas.

The Brain-Body Link

Both swimming and writing depend on the brain’s ability to integrate both hemispheres, the left and right sides.A retained ATNR keeps the body stuck in a primitive one-side-at-a-time pattern. This affects not only coordination but also communication between brain hemispheres, which is essential for sequencing thoughts, spelling, and planning written work.

When we integrate the ATNR reflex through targeted neurodevelopmental exercises, we’re not just improving movement, we’re helping the brain communicate more efficiently. Once the body moves freely across the midline, the mind can do the same with ideas.

Supporting Integration Through Neurodevelopmental Therapy

Therapy focuses on gentle, rhythmic movements that mimic early developmental patterns,  the same ones the brain used to organise itself in infancy. These activities help the nervous system recognise and complete the unfinished reflex cycle.

As the ATNR integrates, we often see:

• More written content, from sentences to paragraphs and pages of writing (depending on age)

• More fluid and coordinated swimming strokes

• Better body rhythm and endurance

• Improved posture and handwriting

• Easier expression of ideas on paper

• Increased confidence and reduced frustration

The Move Learn Connect Approach

At Move Learn Connect, we assess which primitive reflexes are still influencing development and design movement-based programs to integrate them in the correct order. By building from the brainstem up, we help children and adults gain smoother movement, clearer thinking, and greater confidence.

If your child is struggling with swimming, who tires easily or a creative thinker who dreads writing, it may be time to look at what’s happening below the surface. Book a Free Consultation or complete our developmental Questionnaire to explore how neurodevelopmental therapy can support both body and brain integration.