A baby's motor development depends on good muscle tone to hold his head up, roll, sit and perform other milestones. A child with a Sensory Processing Disorder (SPD), specifically the subtype called Postural Disorders may have difficulty maintaining adequate control of her body to meet the demands of motor tasks such as
- maintaining balance while on a moving surface such as a rocking or real horse.
- keeping the head stable in order to visually attend to the environment
- sitting upright to work at a desk without leaning on one arm
Children with postural disorders typically have low muscle tone. This article takes a look at the impact of low muscle tone- also called hypotonia on function and strategies to promote motor skills.
What is Muscle Tone?
Muscle tone is the tension in the muscles that enables us to maintain our posture and resist stretch. It impacts development and function from birth to old age. The tension in a baby's muscles allows him to move his head, arms, and legs away from the floor even though the force of gravity is pulling them downward.
How do you know if your baby has normal muscle tone? His body will have just enough tension to develop these motor skills and eventually sit and stand- but not so much tension that movement becomes difficult.
Parents will discover that their newborn baby continues to prefer the fetal position that she enjoyed so much while developing inside the mother. We can describe this position as one of flexion. It involves the following:
- body curled up
- arms and knees bent
- fists near mouth
Flexion is a position that keeps a baby warm and protected from the environment and enables her to snuggle up to a caregiver and suckle at the breast. It is also an indication that a baby has good muscle tone.
What Causes Hypotonia?
Hypotonia is often indicative of an underlying nervous system, genetic or muscle disorder. Extremely premature babies are at high risk of having neurological problems related to hypotonia.
My son was born 4 weeks early and felt a bit floppy- like a Raggedy Ann doll ! Flexion is a position that keeps a baby warm and protected from the environment and enables him to snuggle up to a caregiver and suckle at the breast. It was important to position him in flexion either in my arms or an infant seat perhaps using pillows or rolled up towels to increase flexion.
It took several months for my son to develop the muscle tone that enabled him to control his head, grasp in midline and grab his feet. However, low muscle tone continued to impact his motor development.
Simply sitting in an upright, supported position helped to strengthen his shoulder, neck and eye muscles. We were able to gradually decrease the amount of support as strength and postural control developed.
The Impact of the Vestibular System
The vestibular system is the sensory system that tells our body how to respond to the pull of gravity and movement of the head. It is also called the balance system.
The receptors for vestibular sensations inside the inner ear enable a child to maintain his balance and respond to the force of gravity. A child's vestibular system tells him that if he leans too far to one side, gravity will make him fall over.
When a young infant is held in the upright, vertical position, the vestibular system detects the pull of gravity. This stimulates the baby to lift his head up, and as he practices this skill, his neck muscles will grow stronger. Sensations from the vertical position and other movements provide information to children necessary to develop motor skills. This is one of the many reasons why baby snugglies and backpack carriers are so wonderful!
A good example of the effects of the vestibular system is when a younger baby enjoys slow calming vestibular stimulation while being carried. Rocking and bouncing cradles and infant swings also help babies to be soothed with gentle vestibular stimulation.
The Benefits of Tummy Time
Tummy Time is a term created by health care professionals to emphasize the importance of babies spending some time everyday positioned on their belies. This position strengthens shoulders, arms and neck musculature helping to promote strength and postural control.
There are a variety of props that can be placed under the chest to help babies and young children tolerate putting weight on their forearms and/or hands. These include:
- a small bolster (as shown above)
- a rolled up towel or cushion or
- a Boppy pillow and
- even your thigh
Older children with low muscle tone continue to benefit from prone positioning, especially when it involves movement.
Hypotonia, Postural Control and W-sitting
An individual's postural control allows his body to move in different directions while remaining stable. Children with hypotonia and a postural disorder may compensate for decreased stability by W-sitting.
W-sitting involves sitting with both knees bent and legs turned outward away from the body, with feet outside the hips so that the legs are in the shape of the letter W.
Positions such as criss-cross, side sitting or long leg sitting are preferable because they develop back and abdominal muscles.
These positions also better enable a child to use both hands together and shift weight from side to side more easily.
Strategies to Promote Muscle Tone and Postural Control
Toddlers and older children benefit from putting weight on their hands even long after they learn to walk and run. Activities such as puzzles may be performed while putting weight on forearms. Coloring in a vertical plane develops postural control, especially while squatting.
Supporting their body weight on their hands provides heavy-pressure sensory stimulation that helps children tolerate touch while also developing coordination between the right and left sides of the body. Encourage children to
- crawl through tunnels
- propel a scooter board while in prone (on belly) position using their hands
- lie prone over a bolster or ball, and rock back and forth, pushing off the floor with their hands
- lie prone on a low swing and push off the ground with their hands to make the swing move
- wheelbarrow-walk- Some children will have enough postural control to walk on their hands with someone holding their ankles. Other children will need to be supported at the thighs or hips.
- Children and adults with low muscle tone may benefit from adapted seating. They may need seating supports to prevent sliding out of the chair! Use of a ball chair or other dynamic seating promotes postural control. Learn more at this blog post: 2019.recyclingot.com/seating-adaptations-for-sensory-processing-disorders/#.XsPgpkBFycw
- Slow, rhythmic movement promotes calm and decreased muscle tone. Fast, erratic movement promotes increased muscle tone. When I performed hippotherapy with children with SPD- I selected horses that excelled at transitions from fast to slow, slow to fast, stop and go and walk over poles so that children with hypotonia experienced erratic vestibular input. Often, clients who started out with rounded, head down, flexion postures, finished with erect postures, better breathing and increased vocalizations.
- Offer activities that involve using force such as pushing, squeezing or pulling heavy objects.
- Encourage an adult child to carry a heavy backpack up and down mountains!