Hypotonia is the medical term for low muscle tone, which refers to the state of muscles throughout the body. Babies with hypotonia are generally diagnosed within the first 6 months of life. Often these infants are described as “floppy” or having a “rag doll” appearance. They may have difficulty holding their body in certain positions or moving to explore their environment. Babies with low muscle tone benefit from seeing a physical therapist as early as possible. Doing so can help them to grow and develop their motor skills. People with hypotonia can live active, fulfilling lives.

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. In addition to testing for hypotonia, physical therapists can provide treatment to improve muscle strength. They also will recommend the best ways to help your child build strength and adapt for low muscle tone at home or school. You can contact a physical therapist directly for an evaluation. To find a physical therapist in your area, visit Find a PT.

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On this page

• What Is Hypotonia?
• Signs and Symptoms
• How Is It Diagnosed?
• How Can a Physical Therapist Help?
• Can This Injury or Condition Be Prevented?
• What Kind of Physical Therapist Do I Need?

What Is Hypotonia?

Hypotonia, or low muscle tone, is the most common motor (movement) disorder of infancy. It may result from damage to, or changes in, the muscles, nerves, spinal cord, or brain during pregnancy.

Muscle tone is the amount of resistance a muscle has to movement. Tone relates to the resistance to stretch in the tendons, muscles, and connective tissue. Muscle tone is essential for holding posture and moving smoothly. Low muscle tone often may be a symptom of other conditions, such as:

• Down syndrome.
• Prader-Willi syndrome.
• Spinal muscular atrophy.
• Cerebral palsy.
• Other medical conditions.

Babies born with low muscle tone but without any other diagnosis or cause are very rare.

Muscle tone does not improve as a baby grows. Once diagnosed with low muscle tone, a person will need to adapt throughout life. One exception is premature infants (born before 37 weeks) who may get diagnosed with hypotonia. Premature infants can develop more typical muscle tone as they grow and develop.

It is important to note muscle tone and muscle strength are not the same thing.

• Muscle tone, or “readiness to move” relates to tendons, muscles, and connective tissue and their resistance to stretching.
• Muscle strength, or the force muscles produce against external resistance, relates to the ability to lift or move objects or our bodies.

A person with hypotonia may be able to lift the same weight as someone with typical muscle tone. The difference is the readiness of their muscles and their body’s ability to prepare to make such movements.

Signs and Symptoms

Generally, children with hypotonia have less resting tension in their muscles than other children. You may notice they have:

• A floppy or “rag doll” appearance. Their arms and legs hang down by their sides.
• Difficulty holding their head upright.
• Trouble sucking or swallowing during feeding.
• Problems breathing or speaking.
• Difficulty holding their body upright to keep an upright posture.
• Flat feet when sitting, standing, and pushing onto their toes.

Hypotonia can be hard to distinguish from weakness in young infants, but you may notice:

• Fewer spontaneous movements.
• More time spent sleeping than other infants their age.
• Reduced or absent reflexes.
• Excessive movements at joints.
• Muscles that are soft and squishy to the touch.
• Difficulty standing with help.

How Is It Diagnosed?

Your child’s doctor or physical therapist will screen for low muscle tone, as it is rare to have hypotonia without another condition. Therefore, another member of your child’s health care team may discover it first. Once you see a physical therapist, they will conduct a full evaluation to assess your child’s condition. This will include gathering information about your child’s health and birth history.

Your physical therapist will conduct a thorough physical exam. This may include tests such as:

• Vertical suspension. When holding the infant under their arms, it feels like the baby could slide through your hands.
• Horizontal suspension. When holding an infant under their chest and tummy, they hang limply over your hands.
• Pull-to-sit assessment. By two months old, when pulling an infant to sitting from lying on their back, they do not attempt to tuck their chin and hold their head as expected. This is related to strength and not muscle tone alone.

Hypotonia cannot be seen on imaging. However, tests (such as an MRI or CT scan) may be used to diagnose conditions that cause or are linked with hypotonia. In some cases, genetic testing and electromyograms, or EMG, may identify abnormalities and help to find a root cause for the low tone.

How Can a Physical Therapist Help?

Your physical therapist will use the best available evidence to develop a treatment program for your child’s needs, challenges, and goals. Most treatments are geared toward increasing strength to compensate for low muscle tone. A physical therapist will work with you to:

• Help your child grow and develop as normally as possible.
• Increase your child’s overall strength.
• Limit further complications.
• Guide you as to when to involve others in your child’s care team. They may recommend professionals such as an occupational therapist, speech therapist, or neurologist.

Your physical therapist also will work with the other members of your health care team as needed.  

Your child’s physical therapy program may include:

Patient and family education. Your physical therapist will guide you on positions and activities that best support your child’s development. These recommendations will be specific to your child’s needs and challenges.

Hands-on therapy. Your physical therapist may teach you how to move, support, and position your child. They also may demonstrate activities to do at home, with specific advice on how to do them.

Muscle strengthening. Your physical therapist may prescribe a specific set of exercises to build your child’s muscle strength and keep them active and healthy.

Can This Injury or Condition Be Prevented?

Hypotonia cannot be prevented. It often is a symptom of another condition or genetic abnormality. However, there is a greater risk of hypotonia for children born too early (before 37 weeks gestation). Follow the advice of your health care provider while pregnant, along with these tips to increase the chance of delivering your baby at full term:

• Avoid tobacco and recreational drugs.
• Eat a well-balanced diet.
• Keep yourself healthy.

If your baby is born with hypotonia, they may not be able to move their body on their own. To help ensure that your child can maintain their health and reach their goals, make sure to:

• Monitor your baby’s body position. This will reduce their risk of developing complications, such as torticollis or flattening of the head.
• Use the strengthening activities taught by your physical therapist in your baby’s daily routine.
• Ensure that they get regular physical activity as they grow. Maintaining an active lifestyle will be important to maintaining health and function as they progress into their teens and adulthood.

What Kind of Physical Therapist Do I Need?

All physical therapists are trained through education and experience to evaluate, manage, and treat various symptoms and conditions. You may want to consider seeing:

• A physical therapist who is experienced in treating hypotonia or the specific underlying condition that is causing your child’s hypotonia.
• A physical therapist who is a board-certified clinical specialist in pediatric physical therapy, or who has completed a residency or fellowship in pediatrics. This physical therapist has advanced knowledge, experience, and skills that may apply to your child’s condition.
• A physical therapist who has a practice that focuses on treating infants and children (pediatrics).

You can find physical therapists in your area with these credentials and clinical expertise through Find a PT, a tool built by the American Physical Therapy Association.

General tips when you're looking for a physical therapist (or any other health care provider):

• Get recommendations from family, friends, or other health care providers.
• Ask about the physical therapist’s experience treating hypotonia.
• Be prepared to describe your child’s symptoms in as much detail as possible. Make a note of what makes the symptoms worse or better.

The APTA Academy of Pediatric Physical Therapy contributed to this consumer resource. It is for informational purposes only and is not intended to represent the position of APTA Pediatrics.