Low Muscle Tone in Babies: Signs, Causes, Milestones & Physical Therapy

I recently had a friend reach out after her toddler was consistently delayed in gross motor skills and was told she had low muscle tone. Like many parents, she immediately started wondering:

What does that actually mean? Is something wrong? Will it get better?

The term hypotonia can sound intimidating, but it's often much less scary than it sounds.

Let's break it down.

Everyone has muscle tone

Muscle tone is the amount of natural tension or resistance present in a muscle when it is at rest.

Some people naturally have:

• Higher muscle tone (hypertonia): muscles feel stiffer at rest.

• Lower muscle tone (hypotonia): muscles feel more relaxed or less resistant to movement.

Having slightly higher or lower muscle tone can be completely normal. Muscle tone exists on a spectrum, and many healthy children fall somewhere along that spectrum.

One important point: muscle tone is not the same as muscle strength. A child can have low muscle tone and still become very strong!

Hypotonia ("Low muscle tone") is more a description than a diagnosis

One of the biggest misconceptions is that hypotonia is a diagnosis by itself. Rather, hypotonia simply describes how a person's muscles feel. It tells us that the muscles have less resting tension than expected, but it doesn't explain why.

Some children have low muscle tone as part of a genetic or neurological condition, while others have lower tone without an underlying medical cause. Your child's pediatrician may recommend additional testing if there are concerns beyond muscle tone alone.

How can Low Muscle Tone impact my child?

Because muscles have less natural tension, children with low muscle tone often have to work a little harder to maintain positions and move against gravity.

This can make activities like tummy time, sitting independently, crawling, standing, and walking feel more challenging or take a little longer to master.

Many children with low muscle tone also tire more quickly because their muscles are working harder to stabilize their bodies. The good news is that children can build strength, coordination, and endurance over time. As they become stronger, many learn to compensate very well for their lower muscle tone.

Signs your baby may have lower tone

Every child is different, and having one of these signs does not necessarily mean your child has hypotonia. However, these are some common characteristics I see as a pediatric physical therapist:

• Delayed gross motor milestones (rolling, sitting, crawling, walking)

• Preferring to sit with legs straight out in front instead of cross-legged

• Appearing very flexible or "floppy"

• Frequently locking the knees when standing

• Ankles that continue to roll inward after several months of standing and walking

• Low endurance during play or gross motor activities

• Difficulty maintaining upright posture for long periods

• Leaning on furniture or caregivers for extra support

• Wanting to change positions frequently because maintaining one position is tiring

Can Low Muscle Tone be Fixed?

This is one of the most common questions parents ask.

Since low muscle tone is a description rather than a disease, there isn't a medication or treatment that changes the muscle tone itself. Instead, the goal is to help your child become stronger, more coordinated, and more confident with movement.

Physical therapy focuses on:

• building strength

• improving balance

• developing coordination

• increasing endurance

• helping your child practice age-appropriate motor skills

Many children with low muscle tone go on to run, jump, climb, play sports, and participate fully in everyday activities.

Will My Child Need Physical Therapy Forever?

One of the questions I hear most often is, "Will my child always need therapy?"

For many children with low muscle tone, the answer is no.

Every child is different, but many babies and toddlers with hypotonia only need physical therapy for a period of time to help them build strength, confidence, and age-appropriate motor skills. Once they reach their goals, they often take a break from therapy and continue practicing through everyday play and activities at home.

Because children with low muscle tone have to work a little harder against gravity, they may benefit from returning to therapy during major developmental leaps or growth spurts. For example, some children need an extra boost when learning to crawl, walk, or navigate stairs. Physical therapy can provide support during times when your child's body is learning new skills.

The goal of therapy is always to help your child become as independent as possible. As they grow stronger and more confident, therapy often becomes less frequent and, for many children, is no longer needed at all.

When should my baby see a physical therapist?

It may be helpful to schedule an evaluation if your baby:

• is consistently behind on gross motor milestones

• seems much more flexible than other babies their age

• tires very quickly during movement

• struggles to keep up with age-appropriate play

• has been told they have low muscle tone and you'd like guidance on how to help

Final Thoughts

Hearing the words "your child has low muscle tone" can feel overwhelming at first. But remember, muscle tone is just one piece of the puzzle.

Many children with hypotonia make wonderful progress with opportunities to strengthen their bodies, practice movement, and receive support when needed.

If you're ever unsure whether your baby's development is on track, don't hesitate to ask your pediatrician or a pediatric physical therapist. Sometimes a few simple exercises can make a big difference!