[Learning from Conversations Between Child Development Staff] Why does the body arch during horizontal bar exercises? The influence of primitive reflexes and support strategies

■ Conversation between instructors
Instructor A:
“I was practicing forward rolls on the horizontal bar with a senior student today... but halfway through, their body started arching. They seemed nervous, but I wonder if that’s a primitive reflex kicking in?”
Instructor B:
“Yeah, that’s a possibility. If it’s arching, the ‘Tonic Labyrinthine Reflex (TLR)’ is more likely to have an effect than the ‘Moro reflex.’”
Instructor A:
“Oh... so it’s not the Moro reflex?”
Instructor B:
“The Moro reflex is mainly a startle response like ‘jumping or clinging,’ which is a bit different from a [sustained arching posture]. When the head position changes, like in horizontal bar exercises, the TLR is more likely to appear.”
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■ Explanation: The relationship between “arching” during horizontal bar exercises and primitive reflexes


relationship
A forward roll on the horizontal bar is an exercise that requires a lot of sensory integration, such as:
・Lowering the head
・Working against gravity
・Gripping and supporting
・Fear of heights
・Core stability
Therefore, it is also a situation where unintegrated primitive reflexes are likely to appear.
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◎ Primitive reflexes often associated with arching
● ① Tonic Labyrinthine Reflex (TLR)
・When the head tilts backward, the body also enters an extension pattern
・When the head moves forward, flexion (curling up) is more likely to occur
→ A forward roll requires “tucking the head and curling the body,” so if the TLR remains, it is easy to arch.


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● ② Spinal Galant Reflex
・The side of the body is prone to arching when tense
・The lower back is prone to an arching posture
→ Reflexes appear due to anxiety or tension on the horizontal bar
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● △ ③ Moro Reflex
・A momentary startle extension due to surprise or fear of falling
→Contraction
・Slightly different from sustained arching → In this case, the TLR is easier to explain than the Moro reflex.

→ Arching the moment you “tuck your head” on the horizontal bar is highly likely to be a reflexive pattern.

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■ Support strategies possible in child development
🟦 1. Creating the sensation of curling the head
・Practice maintaining a forward-roll posture
・Use “look at your belly button” as a cue
・Incorporate play that involves curling the back on a mat
🟦 2. Warm-up exercises for the horizontal bar
・Short-duration hanging
・Hanging while holding the knees (encourages flexion)
・Assisted practice of tucking the head just a little
🟦 3. Posture guidance through verbal cues
・“Round your back”
・“Dango (dumpling) posture”
・“Make yourself small”
→ When the gaze is directed toward the belly button, flexion occurs naturally, reducing arching.
🟦 4. Sense of security in gripping
・For children with weak grip strength, wrap a towel around the bar to make it thicker
・First, create a successful experience of hanging
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■ Summary
・Arching the body during a forward roll on the horizontal bar is often influenced by primitive reflexes (especially TLR).
・The characteristics of the movement are different from the Moro reflex.
・“Creating a posture of tucking the head” and “creating a sensation of flexion” are the keys to support.
・Since anxiety/tension and reflexes are mixed, it is important to support both a sense of security and how to use the body.