An infant or child will get a diagnosis of low muscle tone when:
For a more technical discussion please see Rethinking Low Muscle Tone
Often a child gets a diagnosis of low muscle tone because of one or more movement difficulties
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Pam is a physical therapist, university teacher and grandmother with a passion for sharing sound validated information with parents. Read more
Low muscle tone does not cause any of the behaviors or difficulties listed above.
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.
Children who have been labeled as low toned usually have one or more of the following three underlying conditions:
Hypermobile joints, difficulties with learning new skills and an anxious nature are all part of a person’s makeup. They are there for life.
But here is the good news
Joint hypermobility does not stop a person from doing anything. It just means that you may need to work a little harder to get fit and stay fit. It is just a matter of training.
Children with joint hypermobility often have an anxious nature – so they need to learn about courage and overcoming the tendency to avoid difficult tasks.
Children with coordination difficulties are also able to learn new skills – it takes more time and patience and they may be a little slower at performing some tasks. Having an anxious nature is a challenge but children can be taught ways to deal with their fears and anxieties and not be tripped up by them.
Recognizing joint hypermobility
Fingers that bend back to 90 degrees
Wrist can be bent so that thumb touches the forearm
Knees and elbows bend backwards
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 if often an important underlying cause of some of the difficulties experienced by children with a diagnosis of low muscle tone.
Tight back and hip muscles affect sitting posture in children with joint hypermobility
Let’s go back to the reason your child was labeled "low toned". Most probably there are age appropriate activities that your infant, toddler or child has difficulty performing. It may have been delayed milestones, difficulties with classroom or playground activities, drawing and handwriting or perhaps learning to ride a bicycle. Your child may have attention difficulties.
The only effective way to overcome these performance difficulties is task based training which pays attention to muscle strength and flexibility, fitness and stamina, coordination, persistence and a sense of I-can-do-this.
This allows you as parent to make an important mental shift from a sense of “There is something fundamentally wrong with my child” to a more positive sense of “There are some things my child cannot do today – but with some training these difficulties can be overcome “.
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All you need to know about movement skills training for infants and children
The term muscle tone refers to two aspects of muscles' structure and function.
The term low muscle tone is used when the muscles' stiffness is less than usual (ie it is low) and the readiness for action is also low (muscles respond slowly).
The clinician may make a judgment about a muscle's firmness and inherent stiffness by:
The trouble with these tests is that they are not reliable and do not provide any useful information.
The firmness of a muscle is determined by its inherent stiffness and this in turn depends on the stiffness in the connective tissue sheaths that encase each muscle fiber, hold the bundles of muscle fibers together and connects the muscle to the tendons.
In children with hypermobile joints the connective tissue is less stiff than usual. (It has more give and is more easily stretched).
This tendency for less stiff connective tissue which results in hypermobile (lax) muscles and joints is genetically determined. About 10-15% of people are hypermobile.
The other very important structure that that determines a muscle's firmness and resistance to being stretched is the giant molecule titin.
Titin is a very large elastic molecule found within the muscle cell. The size and strength of the titin molecules is determined by the amount of work a muscle is made to do on a regular basis. Strong muscles have larger and stiffer titin molecules - and this makes the muscle firmer and stiffer. The muscle has better tone.
Generally speaking, strong muscles are firmer and have better tone. It is a common fallacy that you can have strong muscles which are also "low toned". Strengthening a muscle makes it firmer and changes the form of the titin which is component of a muscle fiber which provides the tension and recoil in the muscle.
The term muscle tone is also used to describe the a muscle's readiness for action. This is set by the child's alertness, general level of arousal and readiness for action.
The brain primes the muscles for action by sending signals to the muscles’ sensory receptors. In effect the sensory receptors become more alert and provide more effective sensory feedback and respond more quickly. This allows for the rapid adjustments needed for maintaining balance and postural stability.