Muscle tone is the amount of tension a specific muscle has, according to the Department of Occupational Therapy at Royal Children's Hospital. Having low muscle tone will make it difficult to perform an activity or maintain proper posture. Hypotonia is a state in which the strength of the muscle is severely reduced. Hypotonia can be caused by several factors, including brain damage, muscular dystrophy, and genetic or chromosomal disorders.
Although low muscle tone can affect children and adults, the symptoms might be easier to identify in infants. An infant with low muscle tone will feel similar to a rag doll when picked up, according to Medline Plus. Arms will fall to the side and legs will hang loosely. When placed on his back, an infant with low muscle tone will have trouble picking up his arms or kicking out into the air. He might also have trouble keeping his head straight or raising it up.
People with low muscle tone might have trouble with balance. Some children with low muscle tone eventually learn to walk, as their muscles get stronger and develop over time. Others might never walk on their own and require the help of a walker or wheelchair. Because of ligament and joint laxity, maintaining the proper posture to ensure balance might be difficult. When the neck also lacks muscle tone, people with low muscle tone will have a hard time controlling head movement. Although adults might be able to deal with this, the lack of control over head movement might cause children to lose balance and fall.
Because muscle tone is required for many basic motor skills, a child with low muscle tone will have trouble lifting his head, sitting up, rolling on his stomach and crawling. The developmental delay also affects fine motor skills and might cause trouble in things that require coordination, such as using scissors, holding on to a pencil or dressing themselves. People with low muscle tone do not necessarily have mental retardation, but they might have trouble talking or eating because their jaws are not strong enough.
Although many people with low muscle tone will be able to walk, they might get tired easily when trying strenuous physical sports or activities. They might feel like their legs are "giving up under them" when trying to run or play an involved sport. Low muscle tone can also increase the risk of hip and neck dislocations, as the muscles don't have the strength to support the skeleton and protect it during movement.
- Baby Center: What is "Low Muscle Tone" and What Does it Mean?
- Skills for Action: Low Muscle Tone
- Children's Hospital Boston: Muscle Weakness (Hypotonia)
- National Institute of Neurological Disorders and Stroke: NINDS Hypotonia Information Page
- MedLine Plus: Hypotonia
- Department of Occupational Therapy, Royal Children’s Hospital: Activity Ideas for Low Muscle Tone