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Low Muscle Tone Article

This fabulous article was posted on the Child Hypotonia Board.  It explains very clearly exactly what low muscle tone is--an important thing for we parents of hypotonic kids to understand!  Thanks to "nbinuk" for posting it!

By Diane E Gagnon, M.Ed., PT (Physiotherapist) Biddeford, Maine 04005, USA Many people don't understand the difference between muscle tone and muscle strength.

True muscle tone is the inherent ability of the muscle to respond to a stretch. For example, if you quickly straighten the flexed elbow of an unsuspecting child with normal tone, the biceps will quickly contract in response (automatic protection against possible injury). When the perceived danger has passed, which the brain figures out really quickly once the stimulus is removed, the muscle then relaxes, and returns to its normal resting state.

The child with high tone or "spasticity" has over-reactive response to the same stimulus. When his arm is stretched, the biceps tightens at an even more rapid rate, and the rate of recovery is much slower, even after the stimulus is removed. Full relaxation is difficult to achieve, so the muscle stays taut for an extended period of time. If another stimulus is added before the muscle has a chance to recover (which happens often during normal movement in the everyday world), the muscle contracts again, becoming tighter. Because this child's muscles never truly rest unless he is asleep, the long term result is tighter, shorter muscles with reduced joint range. This is typically seen in the child with spastic CP.

The child with low tone has muscles that are slow to initiate a muscle contraction, contract very slowly in response to a stimulus, and can not maintain a contraction for as long as his "normal "peers.

Because these low-toned muscles do not fully contract before they again relax (muscle accommodates to the stimulus and so shuts down again), they remain loose and very stretchy, never realising their full potential of maintaining a muscle contraction over time.

These are the "floppy" children who have difficulty maintaining any posture without external support.

A child's unique neurological wiring determines whether he will be low, high, or normal toned. Most people have "Normal Tone". In those who do not, a number of factors are involved. Somewhere deep in the muscle are receptors responsible for detecting changes in muscle length. These receptors then tell the brain there is a stimulus, and the brain tells the muscle to contract in response. There are numerous feedback loops to tell the brain whether the muscle has responded appropriately, needs to contract again, relax or whatever... In addition, there are receptors that tell where each joint is located in relation to all the other body parts that help to determine position in space, etc. A delay in perception, decoding, or transmission anywhere along the neural pathways will result in a change from an optimal response, or "normal" tone.

People often refer to having a "toned" body when they are in "good physical condition" and exercise regularly. Their muscles are taut, and they look lean.

An out of shape person is referred to as having "poor tone", with fleshy muscles and an abundance of "fat". Neurologically these people actually have the same "tone", and the fat person is inherently capable of looking as "toned" as the other (with some allowances made for genetic make-up of course), and just needs to exercise regularly. Fitness experts and health clubs will tell you they are "improving muscle tone", when they are actually reducing the amount of fat to lean body mass ratio. You can improve your fat to lean body mass ratio, and you can become stronger too. These are under your voluntary control.

Muscle tone occurs at an involuntary level. We can effect changes in muscle responses with sensory integration treatment techniques that increase the "alert state of the muscle" by bombarding it with sensory stimuli and improve the brains ability to perceive changes in muscle length, preventing it from accommodating to stimuli.

With ongoing treatment and practice throughout the day, the more "normal" response elicited, the stronger and more efficient even low toned muscles become. "That" is the basis of our classroom program for children with low tone. Sensory bombardment can effect changes in perception that then lead to changes in efficiency along the neural pathways. But it goes way beyond a couple of hours a week in the gym.

1999 Diane E. Gagnon, M.Ed., PT Biddeford, Maine 04005, USA

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