My child has been diagnosed with low muscle tone. What does this mean?

Author  Pam Versfeld  MSc (Physio) UCT,  Physical Therapist  Read more 

Low muscle tone is often used to explain the difficulties some children experience performing everyday tasks, sitting erect with ease and comfort, or have poor endurance, strength and mental stamina. In this article I provide an alternative explanation for these difficulties. 

Who gets a diagnosis of low muscle tone?

An infant or child will get a diagnosis of low muscle tone when:

  • The muscles appear to be less firm than usual
  • The child appears to be floppy and to have loose joints
  • The child appears to be less alert and have poor posture and attention

For a more technical discussion please see Rethinking Low Muscle Tone

When does a child get a diagnosis of low muscle tone? 

► May be  late achieving the major milestones- but not always

► May be late learning to walk

► Has trouble sitting erect and working at a table - tends to sit with back rounded, may lean on one hand when drawing and writing

► May have flat feet and complain of foot pain with walking 

► Has difficulty sitting still, tends to fidget, does not complete school tasks

► Has difficulties with handwriting and drawing 

► May tire very quickly, not like walking far, have trouble going up stairs

► May be good at games that involve short bursts of running, but have difficulty with posture in sitting, drawing and handwriting - these tasks require sustained activity in the postural muscles

► Sits between legs on floor (w-sitting), does not like cross legged sitting

► Appears to have poor attention span or concentration, gives up easily

► Cannot hang on the monkey bars, does not like climbing on the jungle gym, is fearful

► Complain of leg pain after exercise, knee pain at night. 

► Have weak core muscles and poor core stability  

► Have difficulties learning ball skills

Low muscle tone does not cause any of these motor difficulties

The first thing to understand is that low muscle tone is a not a condition or a diagnosis. There are a number of conditions that affect the brain and muscles where hypotonia (low muscle tone) is a symptom.  The child appears to be floppy and there are other signs and symptoms that indicate that the child has a neurological disorder including significant developmental delay, altered reflexes and cognitive difficulties.  

Low muscle tone is not a diagnosis 

It is important to understand that low muscle tone should never be used as a diagnosis.

  • There is no health condition called low muscle tone.
  • There are no diagnostic criteria to describe such a condition. 
  • Low muscle tone cannot be measured.

Nowhere will you find a good reason for why your child has low muscle tone. You will also not find any effective treatment being described.

So why did my doctor or therapist say that my child has low muscle tone? 

The term "low muscle tone" is still widely used by doctors, physical and occupational therapists. This is because for many years the reason why children, with no identified muscle or neurological disorder, presented with movement and postural difficulties, developmental delay and weakness, was not well understood.

Today, however, the impact of joint hypermobility on muscles, posture and movement and even on behavior is well documented. We also know that a muscle's tone comes from a the giant muscle protein called titin. 

For a more detailed and referenced argument about the misuse of the low muscle tone diagnosis and the importance of Titin see: Rethinking Low Muscle Tone  

If it is not low muscle tone, what is causing my child’s movement difficulties?

The majority of children who have been labeled as low toned usually have one or more of the following fairly common underlying conditions: generalized joint hypermobility, developmental coordination disorder, associated with a very cautious, fearful nature. 

Joint hypermobility is the most common reason for a low muscle tone diagnosis

Joint hypermobility is probably the most common condition that causes the difficulties experienced by children with a diagnosis of low muscle tone.

Joint hypermobility simply means that structures that hold the joint together are more pliable than normal and provide less support for the joints.

However, in most instances strengthening the muscles not only provides the added support that joints need for good posture and movement, but also increases the inherent stiffness in the muscle and joint connective tissue. 

There is one other very important aspect of joint hypermobility. Despite the increased flexibility, the child will usually have some tight muscles. This is the reason why children with generalized joint hypermobility have tightness in the hip muscle, including tight hamstrings and tightness in the muscles that cross from the lower back over the side of the hips. this tightness makes sitting erect difficult. and uncomfortable. 

So for most children with a diagnosis of low muscle tone, the best approach to improving posture and motor control is a program of exercises to strengthen weak muscles on the one hand and stretch tight muscles on the other. A fitness training program is particularly important for inactive children who are at risk for obesity and low bone density.  Read more

Recognizing joint hypermobility

Elbows and knees bend backwards.

elbow extension.jpg

Child may have a hollow back and flat feet, and poor standing posture. 

Child-stand-hollow-back.jpg Wrist and finger joints bend further than usual.      

hypermobile hands.jpg  Hypermobil hand 1.jpg

Developmental coordination disorder (DCD)

There are a group of children who have difficulties with coordination and with learning new skills which affects their function and participation at home, at school and in the playground. 

Children with DCD have difficulties with the control of posture, with balance and agility tasks as well as fine motor activities and handwriting. They may also avoid participating in playground games and as a result have poor fitness levels.

Research has shown that the most effective approaches  to improve the coordination of children with DCD are task oriented  intervention programs which targets specific skills.  Read more

A very cautious/anxious nature: the highly sensitive child

Children with low muscle tone, joint hypermobility and DCD often have a very cautious and sometimes fearful nature, leading to a raft of emotional and behavior difficulties which interfere with everyday and school function. 

Recognizing and understanding the impact of fearfulness and anxiety on behavior allows parents to implement strategies to help their children overcome their fears and learn to take on challenges. Read more

Low muscle tone is not caused by a sensory processing disorder

Children who have been given a diagnosis of low muscle tone, also often have are diagnosed with a sensory processing disorder.  However there is no valid scientific argument that links muscle tone to disordered sensory processing. Read more  

Hypermobile joints and tight muscles 

Sometimes joint hypermobility is missed because the child appears to have tight muscles. It is important to understand tight muscles is a common feature of joint hypermobility, especially in the muscles crossing the back and sides of the hips.  It is also important to understand that this muscle tightness can be an important underlying cause of some of the difficulties experienced by children with a "diagnosis" of low muscle tone. 

Poor sitting posture is usually caused by a mixture of tightness, weakness and sometimes poor coordination.  My child can't sit up straight and fidgets a lot at school. What is the reason?

T sitting slumped_2.jpg

What about infants diagnosed with low muscle tone?

Infants who appear to be floppy, have very lax joints and are slow to reach their major milestones on time are often given a diagnosis of "low muscle tone".   Very often these infants have a combination of pre-mature birth, joint hypermobility, a very cautious nature and sometimes early symptoms of autism.

Whatever the underlying reason for your infant's movement difficulties early intervention is important.  Early intervention helps to prevent the long term impact of developmental delay on attention and coordination difficulties which often surface just when the child enters school. Read more

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