Believe it or not, there are more than 600 muscles in the human body. These muscles control everything from digestion and the pumping of blood throughout our bodies to the way we move. These muscles are divided into 3 different types: smooth muscle, cardiac muscle, and skeletal muscle.
Smooth Muscle
Smooth muscle controls many of our bodily functions like digestion and urination. These muscles are not under our voluntary control. Instead, our brain controls these muscles without us even realizing it is happening.
Cardiac Muscle
Cardiac muscle does what you would expect. It allows our heart to contract and relax to pump oxygenated blood throughout our body. Just like with smooth muscle, cardiac muscle is not under our voluntary control. The brain and a special group of cells within the heart, called pacemaker cells, control the functions of the heart.
Skeletal Muscle
The remainder of the muscles in our body are called skeletal muscles, and they are under our voluntary control. Muscles like our biceps and quadriceps are activated when we choose to lift a weight at the gym, play a game of soccer, or sweep the floor.
Understanding Muscle Tone
Whether we are actively participating in a game of soccer or relaxing on the sofa watching TV, our brain, nerves, and muscles are working together to keep our body in the correct position and moving in the ways we want it to. And this is where the concept of muscle tone comes in.
When we are laying on the sofa watching TV, our muscles are relaxed, unlike when we are playing that game of soccer. And although we are in this relaxed state, our muscles continue to have a small amount of tension in them. And this small amount of tension is called muscle tone. This resting amount of muscle tone or tension, allows our bodies to resist gravity. Without this resting tone, we would be a puddle on the ground.
The amount of tone within the body’s muscles is controlled neurologically and is unique to each person. The amount of muscle tone an individual has falls within a range of what is considered “typical”. Some of us have muscles that have a higher tone to them while others have a lower amount of tone.
There are conditions in which a person’s muscle tone can be outside that range of “typical”. Muscles with too much tension are categorized as “high tone” and muscles with too little tension are categorized as “low tone”.
When high muscle tone is present, the resting/relaxed tension/tone in the muscle is high. In many cases, it feels as if the muscle is contracting like it would during activity. Due to this high degree of muscle tone, active movement is more difficult. When the brain signals the muscle to contract, there is a significant amount of force needed to overcome that resting position due to the increased tone. Individuals with high muscle tone are often diagnosed with conditions that affect the brain and spinal cord such as Cerebral Palsy, Strokes, or Multiple Sclerosis.
When low muscle tone is present, the resting/relaxed tension/tone in the muscle is low. The muscle often appears mushy and floppy. Due to this decreased muscle tone, active movement is more difficult. When the brain signals the muscle to contract, the resting tone is not present so each action requires more force to get to the resting position and then into the active movement. Individuals with low muscle tone may be diagnosed with conditions such as Down Syndrome, Cerebral Palsy, Muscular Dystrophy, or Prader-Willie syndrome.
The best way to understand what atypical muscle tone looks like is in terms of kicking a ball. An individual with typical muscle tone begins at point A (rest), then activates the Quad to extend their knee so they can kick the ball. A person with low tone begins at point B and has to activate their quad to get to point A (the rest position) and then beyond it to kick. This means that the energy requirement for them is significantly greater than the individual with typical muscle tone.
The person with high muscle tone also begins at point B but with a different set of challenges. They have to activate the quad with enough force to overcome the extra tension in the quad to extend the knee. At the same time their hamstring muscles (which flex the knee) have an increased level of tone in them as well. So they also needed the added force to work against the hamstrings which are trying to keep the knee bent. Again the energy requirement and effort needed to move if significantly greater than individuals with typical muscle tone.
Muscle tone itself is controlled neurologically. It is not something that can be changed or fixed through therapy. But, that does not that mean children with low or high muscle tone cannot benefit from therapy. Instead the expectation and understanding of what is being addressed and worked on needs to be clear. Therapy is aimed at helping children with low or high muscle tone function at their highest level in spite of the tone.
So, how do we do that?
Well, the treatment for each child is different and specific to their age and medical history. But, there are some general categories that we do address:
Strength:
Muscle tone and muscle strength are not the same. While muscle tone is an involuntary characteristic of muscle, strength is voluntary. We define muscle strength as the ability of a muscle to contract and create force. The force of that contraction can be changed through strength activities.
Children with low and high muscle tone can often benefit from strengthening activities to address deficits in their movement abilities. Thinking about our example of kicking, the tone in that quad muscle is not going to change, but the strength of that muscle, it’s ability to create force through a contraction, can be changed. And this strength can help compensate for some of the effects of the muscle tone.
It’s very important to remember that a child with atypical muscle tone can become fatigued very easily. The effort it takes to contract their muscle and perform a movement is far greater than individuals with typical muscle tone. This fatigue should always be validated and monitored.
Posture and Position:
Muscle tone that falls outside of the range of typical can lead to problems with posture and position. Individuals with low muscle tone can have difficulty maintaining an upright aligned position for prolonged periods of time. They often demonstrate a slouch posture with components such as a forward head, hunched shoulders, protruding belly, and kyphotic spine. Individuals with high muscle tone can often move into postures that are dictated by the muscle groups with the highest tone. For example, high tone in the hamstrings can keep the knees in a bent or flexed position and lead to a crouched position when walking.
Therapy can work on strength to improve these postures and provide adaptive equipment to support the child in alignment when their muscles are not able to.
Balance and Coordination:
Children with atypical muscle tone can often have difficulty with skills that require balance and coordination. The altered level of tone in their muscles means that their muscles don’t react as quickly as they need to when performing an activity that requires balance and coordination skills. So through strengthening, skill practice, and other techniques therapists help children improve their abilities in this area.
So, that was a lot of information on a subject that can be very confusing. It boils down to this:
- Muscle tone is not under our voluntary control. It is controlled by our neurologic system.
- Muscle strength is voluntary and can be changed through strength training activities.
- Muscle tone falls within a range of typical.
- If tone falls out of the range of typical it can be either too low or too high.
- While therapy cannot change the amount of tone in a muscle, it can improve an individual’s movement and function.
-Heather