Why Do So Many Kids with Poor Muscle Tone Have Retained Primitive Reflexes?

This article provides helpful information on how self-esteem is affected by retained Primitive Reflexes. Integrated Learning Strategies (ILS) is a learning and academic center. As a reminder, ILS is not a health care provider and none of our materials or services provide a diagnosis or treatment of a specific condition or learning challenge you may see in your child or student. If you seek a diagnosis or treatment for your child or student, please contact a trained professional who can provide an evaluation of the child.

If you have worked with children who have low muscle tone, you probably noticed a common pattern. Many of these children also demonstrate signs often associated with retained Primitive Reflexes. If Primitive Reflexes are retained, you probably see kids struggle with the following:

• Sitting upright
• Tires easily
• Avoids playground activities
• Has poor coordination
• Finds it difficult to focus during table-top tasks

While primitive reflexes are only one piece of a much larger developmental picture, understanding how muscle tone, core strength, postural control, and early movement patterns work together can help parents and professionals better support a child’s development.

What’s Behind Poor Muscle Tone?

Poor muscle tone, also known as hypotonia, doesn’t mean a child is weak. Muscle tone refers to the amount of tension present in muscles when they are at rest. Children with low muscle tone often have muscles that feel “floppy” and require more effort to maintain posture and stability.

There are many reasons a child may have poor muscle tone. Some of those reasons may include the following:

• Genetics
• Premature birth
• Neurological differences
• Connective tissue disorders
• Developmental delays
• Sensory processing differences
• Certain medical conditions

In many children, no single cause is known, but the impact on movement and daily function can still be significant.

Because maintaining posture requires constant muscle activation, children with low muscle tone often compensate by locking their joints, leaning on furniture, sitting in a “W” position, or avoiding physically demanding activities altogether.

Signs You May See with Poor Muscle Tone

There are many signs that can clue you in if a child has poor muscle tone. Children with low muscle tone may demonstrate a wide variety of signs that may include the following:

• Slouching or difficulty sitting upright
• Frequent leaning on desks or adults
• Poor balance
• Delayed gross motor milestones
• Difficulty running, jumping, hopping, or climbing
• Fatigue during physical activities
• Weak core strength
• Poor endurance
• Challenges with handwriting
• Difficulty maintaining attention during seated tasks
• Poor coordination
• Frequent tripping or falling
• Open-mouth posture
• Difficulty with bilateral coordination
• Trouble crossing midline

While each child is unique and different, challenges may vary. However, many kids with poor postural stability and muscle tone often have one or more retained Primitive Reflexes.

Why Working with Kids Who have Poor Muscle Tone may be Challenging

Children with poor muscle tone are often working much harder than they appear.

Imagine trying to solve a puzzle while constantly trying not to fall out of your chair. That extra effort leaves fewer resources available for attention, learning, and fine motor tasks.

Because their bodies don’t automatically provide enough stability, these children often have to consciously think about maintaining posture while completing everyday activities.

When a child has poor muscle tone, you may find gaps in the following areas:

• Learning
• Attention
• Emotional regulation
• Endurance
• Motor planning
• Coordination
• Self-confidence

Therapy sessions can also become challenging because children fatigue more quickly. Activities that seem simple may require significantly more physical effort, making it harder for them to stay engaged or complete tasks successfully. Parents and therapists may have to do more to help kids with poor muscle tone when working on therapy exercises and activities. Many times, you may be required to lift, pull, push, or stabilize the child’s limbs or body movements to ensure they are getting the full benefits of the exercises and activities.

Supporting posture and core strength often improves a child’s ability to participate in therapy, school, and play.

The Connection Between Poor Core Strength and Retained Primitive Reflexes

Primitive reflexes are automatic movement patterns present during infancy that help babies survive and develop. As children gain strength, postural control, and voluntary movement, these reflexes are typically integrated, allowing more mature movement patterns to emerge.

Although the relationship is complex and not fully understood, therapists have observed that children with poor postural stability and core weakness may also demonstrate behaviors commonly associated with retained Primitive Reflexes.

Strong postural muscles provide the stable foundation needed for controlled movement. When that foundation is weak, it may be more difficult for children to develop efficient movement patterns that support reflex integration.

Rather than viewing retained reflexes as the cause of poor muscle tone, it’s often more helpful to consider both as part of an interconnected developmental system involving the brain, muscles, balance, sensory processing, and motor control.

Primitive Reflexes Commonly Impacted by Poor Core Strength

Several primitive reflexes rely heavily on postural control and trunk stability as children develop. The reflexes impacting muscle tone and core strength the most include the following:

Tonic Labyrinthine Reflex (TLR)

The TLR reflex strongly influences posture, muscle tone, balance, and head position. When a TLR reflex is retained, you may find the following impacting muscle tone:

• Slouch frequently
• Have poor balance
• Tire easily
• Struggle with core activation
• Have difficulty climbing or navigating stairs

Symmetrical Tonic Neck Reflex (STNR)

Because the STNR reflex supports the transition into crawling, it may impact the development of muscle tone as the child grows and develops. When the STNR reflex is retained, you may see kids doing following:

• Slumps over their desks
• W-sits frequently
• Has weak core muscles
• Avoids crawling-like activities
• Demonstrates poor posture during handwriting

Asymmetrical Tonic Neck Reflex (ATNR)

The ATNR reflex assists early eye-hand coordination during infancy. Because muscle tone and core strength support eye-hand coordination and handwriting development, a retained ATNR can delay or prevent a child from excelling in these areas.

Many children with a retained ATNR reflex, struggle with the following:

• Crossing the midline
• Bilateral coordination
• Handwriting and fine motor
• Rotating the entire body instead of separating head and arm movements

Spinal Galant Reflex

The Spinal Galant reflex contributes to early trunk movement. When retained, it may lead to a child having trouble sitting for long periods of time in school, especially when they have poor muscle tone.

A retained Spinal Galant reflex may cause a child to do the following:

• Fidget constantly in their chair
• Cause sensitivities to waistbands or clothing
• Has difficulty sitting still
• Shows reduced trunk stability

Moro Reflex

The Moro reflex may also contribute to poor muscle tone, especially if the child is delayed in sensor development. Children with a retained Moro reflex may have difficulty with the following:

• Becomes easily overwhelmed
• Fatigues quickly
• Demonstrates poor postural endurance
• Has trouble regulating attention during movement tasks

Supporting Children with Poor Muscle Tone

Building core strength isn’t just about doing sit-ups or planks, especially those who have retained Primitive Reflexes. Children benefit most from movement experiences that challenge balance, coordination, body awareness, and postural control in fun and meaningful ways. However, if retained reflexes are present, the child must also perform certain exercises to fully integrate the reflexes that contribute to poor muscle tone. To know if a child has poor core strength, you can test them here.

To learn more about targeted exercises that can help integrate these reflexes, click here.

For additional activities that can support poor muscle tone, but don’t integrate the reflexes, try the following:

• Obstacle courses
• Crawling games
• Climbing
• Wheelbarrow walking
• Animal walks
• Swinging activities
• Balance challenges
• Heavy work activities
• Yoga for children
• Playground play

Reflex integration activities should also be done alongside strength, balance, and functional movement training as part of a comprehensive treatment approach.

Poor muscle tone affects far more than posture. It influences how children move, learn, play, and participate in everyday life. While retained primitive reflexes are not the sole explanation for hypotonia or developmental challenges, they can be one factor therapists consider when evaluating a child’s movement patterns.

By looking at the whole child, including muscle tone, core strength, balance, sensory processing, motor planning, and reflex development, we can create interventions that build stronger foundations for lifelong movement and participation.

Every child develops at their own pace, and with the right support, many children with poor muscle tone can make meaningful gains in strength, confidence, coordination, and independence.

Retained Primitive Reflexes Roadmap

For more information on the signs and symptoms of six retained Primitive reflexes, complete the form below to download a free copy of our Retained Primitive Reflexes Roadmap. When you’ve completed the form, check your email inbox for the download link, including your junk and spam folder. If you do not see the download link come to your email inbox, please email us at info@ilslearning.com.

Reference Materials

Bartlett, D. J. (1997). Primitive reflexes and early motor development. Journal of Developmental & Behavioral Pediatrics, 18(3), 151–157. https://doi.org/10.1097/00004703-199706000-00002

Marquis, P. J., Ruiz, N. A., Lundy, M. S., & Dillard, R. G. (1984). Retention of primitive reflexes and delayed motor development in very low birth weight infants. Journal of Developmental & Behavioral Pediatrics, 5(3), 124–126. https://pubmed.ncbi.nlm.nih.gov/6736257

Gieysztor, E. Z., Choińska, A. M., & Paprocka-Borowicz, M. (2018). Persistence of primitive reflexes and associated motor problems in healthy preschool children. Archives of Medical Science, 14(1), 167–173. https://pubmed.ncbi.nlm.nih.gov/29379547/

Provazník, A., Musálek, M., Bob, P., Větrovský, T., Malambo, C., Silva, A. F., & Anderson, D. (2026). Persisting primitive reflexes and motor and cognitive development in children: A systematic review. Acta Psychologica, 266, Article 106915. https://doi.org/10.1016/j.actpsy.2026.106915

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