Please Stop Saying “TONE”!

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If you’ve been around the gym a bit or you’ve been in the health-fitness-exercise field for any length of time you could probably retire if you had $1 for every time you heard someone say “I don’t want to get big, I just want to tone” or its myriad variations.

In this piece we’ll examine what tone actually is and it’s positive and negative aspects as well as try to examine what people really mean when they say that “tone” is something they want and what they may think the opposite of tone is – hypertrophy?

muscle tone

syn tonus (1) in skeletal muscle, a state of tension that is maintained continuouslyminimally evenwhen relaxedand which increases in resistance to passive stretch. Pathologically, loss of tone (flaccidity) can be caused,e.g. by peripheral nerve damage, and exaggerated tone (spasticity) by overstimulation, e.g. when the activity of the relevantlower motor neurons is released from higher CNS control in spinal injury. The term is sometimes also used, incorrectly, toindicate general muscle strength. (2) In smooth muscle, steady tension maintained in the walls of hollow vessels; regulatedmainly by autonomic innervation but influenced, e.g. in the walls of arterioles, by local variables: temperature, chemicalfactors or intravascular pressure, contributing to autoregulation of appropriate blood flow. See also stretch reflex.

Dictionary of Sport and Exercise Science and Medicine by Churchill Livingstone © 2008 Elsevier Limited. All rights reserved.
To get a visual of this concept, we have to understand the structure of our muscles and how the nervous system controls them. Skeletal muscle cells are long cylindrical cells that for the most part run the length of the muscle. They have a connective tissue covering called the endomycium. Muscle cells within any given muscle are grouped together into units called fasicles and these fasicles are also covered with a connective tissue called the perimycium. Groups of the groups of muscles cells (fasicles) make up the muscle itself and are covered with a connective tissue called the epimycium.
The connective tissues (endomycium, perimycium and epimycium) combine with each other at the ends of the muscle cells to form tendons which attach the muscle (muscle cells) to the bones and allow the contraction of the muscles cells to rotate the bones around the access of the body’s joints.
The nervous system and it’s nerve cells control the muscle cells. Each motor neuron and the muscle cells it innervates (attaches to) are called a motor unit. Some motor units and motor neurons control 1,000 muscle cells and some only control one muscle cell. In large muscles of the legs and torso where a gross or more general control is required we have fewer but large motor units. In muscles of the face, mouth, and hands where we require a fine tuned control, the motor units are small (one neuron for one muscle cell) and we have many of them so we can exert a very fine tuned control over the contraction (movement and tone) of those muscles.
The resting tone of a muscle is maintained by the asynchronous firing of the motor units within that muscle when it is not being told to contract voluntarily. It would look something like this.
Exercise, especially resistance training does have an effect on tone. But, it is not in the obvious way that the people that would say something like “I just want to tone, I don’t want to get big” may think.

The Motor Learning Effect

The motor learning effect is the reason that people gain strength in the initial stages of a resistance training program. This effect is most pronounced in people that were “un-trained” before they started the program. The gains in strength that these exercises have during the first stages of their program are because of the nervous system finding and recruiting motor units that it hasn’t used in a long time. The individual does not grow new muscle cells, new nerve cells or new motor units. Instead, due to the “overload” or the demands the new program puts on the person’s body causes the person to adapt by finding motor units that they haven’t been using. Now that the person can recruit this additional, previously un-utilized or under utilized motor units they can do more work or are stronger. Additionally, now that they have a larger pool of available motor units, their tone may improve because there are more motor units to do the asynchronous firing that creates the appearance of tone. This new level of resting tone, would be maintained in this manner.

After the first six weeks of a program, additional gains in strength will typically come from changes in the muscles cells themselves. That is the muscle cells must add contractile proteins (actin and myosin) organized in structures called sarcomeres that give them skeletal muscles their stripped or striated appearance. It’s much more difficult to get the muscle cells to hypertrophy or grow larger from adding contractile proteins. It requires taking in the right type, quality and quantity of nutrients, getting the right amount of sleep to maximize hormone levels for recovery and adaptation in the form of growth as well as the consistency of following a challenging resistance training program designed for hypertrophy. Not all resistance training programs are designed for hypertrophy. Programs can also be designed for improving muscular endurance, strength and power. The weight on the bar is only one of the many variables that is manipulated in program design and it is not the most important variable for hypertrophy programs. See also Strength and Why You Need It and The Truth About Body Weight Exercises.

So, it seems that the word Tone has been confused and combined by many with the concept of Hypertrophy. Now that we’ve established the difference, let’s talk about tone and it’s real implications.

Hypertonicity, Hypotonicity, Flaccidity and Spasticity

Tone can be conceptualized as a spectrum, a range or a scale. The middle of the scale would be normal, healthy average tone. The far left would be the absence of tone or flaccidity which is often the result of nerve damage and the far right of the scale would be spasticity or constant contraction of the muscle. The spastic condition is often the result of damage to the central nervous system. When a person says the want to tone, I don’t think they mean that they want to move toward the right of the scale towards a spastic condition of the muscle/s. It’s interesting that a neurological concept and term “tone” or “tonicity” has been coopted into a discussion of asthetics.

Cerebral Palsy, Multiple Sclerosis, Strokes and other central nervous system conditions often result in a hypertonic state of muscle or spasticity. Often the flexor muscles or the extensor muscles are hyperactive together resulting in a flexor spasticity or an extensor spasticity and the goal of treatment is to lower or decrease the tone of the muscles. Nerve damage to the nerves in the extremities from trauma or Polio may result in faccidity or hypotonicity where no signals can get to the muscle cells and therefore there is no tone at all or a diminished tone. The concepts of tone and hypertrophy are very different though one form of muscular dystrophy (Duchenne Muscular Dystrophy) connects the concepts in it’s symptoms. Duchenne Muscular Dystrophy is sometimes called the pseudohypertrophic type because the flaccid weak muscles seem to get larger or hypertrophy due to a build up of scar tissue.

Facilitation, Inhibition, Recovery and Contracture

Tone is a function of the nervous system and changes throughout the day, minute to minute, hour to hour. We try to maintain homeostasis of tone when at rest and adjust our tone upward or downward based on the needs of the activity and environment. Despite our best efforts and homeostatic mechanisms our tone does not always meet the demands of the circumstances and can snowball out of control.

 Facilitation, Warm Up and EPSPs –

The neurons that control your muscle cells, the ones that are part of the motor unit and directly connect to the muscle cells get signals from lots of other neurons in your central nervous system telling them what to do. These lower motor neurons, the ones that are part of the motor unit and directly attach to the muscle cells are getting signals from many different upper motor neurons (neurons of the central nervous system) as well as from sensory neurons coming from proprioceptors in the muscles themselves. Golgi Tendon Organs (GTOs) and Muscle Spindle Organs (MSOs) are the main proprioceptors that work as a servomechanism to help maintain normal levels of muscle tone. The GTOs make sure your tone doesn’t get to high by inhibiting the lower motor neurons and the muscle spindles make sure your tone doesn’t get to low by exciting the lower motor neurons.

There are of course times that we want to have more than the normal amount of tone so that our muscles are ready to contract without delay. This is accomplished by signals coming down the spinal cord upper motor neurons to the lower motor neurons and causing the lower motor neurons to fire more signals per second. This in turn cause the tone in the muscle to increase. The motor units are on ready. Facilitation of the lower motor neurons, bringing them closer to threshold and increasing their rate of firing is one of the results of and reasons for doing a warm up, movement prep, or the “activation” exercises that many trainers and therapist talk about. It’s also important to note that stress and worry will also cause more signals to travel down the upper motor neurons and facilitate the lower motor neurons increasing the resting tone of the muscles. This is one reason people often report a stiff, tight, or sore neck and shoulders when under stress for prolonged periods.

An Excitatory Post Synaptic Potential is what we call it when a neuron, in this case the lower motor neuron, is above it’s normal resting potential (-70mv) and closer to its threshold (the level at which it will fire an impulse.) Being close to its threshold or having an EPSP means that the neuron will fire more signals per second and in the case of this discussion, cause more motor units to contract and increase the resting tone.

Inhibition, Cool down and IPSPs –

Conversely, there are upper motor neurons that cause inhibition of the lower motor neurons. Parkinson’s disease illustrates the important function of these inhibitory upper motor neurons because the tremors and the eventual freezing or motor block is a function of too much tone or signals to the muscles because of a lack of inhibitory signals. The GTOs, the proprioceptor that causes inhibition is also important for lowering the firing rate of lower motor neurons, moving them further away from threshold and decreasing tone.

When we stretch and do other cool down activities like deep breathing, guided relaxation or a variety of recovery modalities like heat, cold, compression we can slow the firing of the excitatory neurons and increase the firing of the inhibitory upper motor neurons and the GTOs to slow the firing of the lower motor neurons and decrease the tone of the muscle. In this case, decreasing the tone of the muscle can help to switch it from catabolic energy expenditure mode to anabolic energy conservation and repair mode. Passive stretching and even foam rolling can stimulate the GTOs and increase inhibitory signals. More on this in Part 2.

An Inhibitory Post Synaptic Potential is what we call it when a neuron, in this case the lower motor neuron, is below it’s normal resting potential (-70mv) and farther away from its threshold (the level at which it will fire an impulse.) Being farther away from its threshold or having an IPSP means that the neuron will fire fewer signals per second and in the case of this discussion, cause the motor units to contract less frequently and decrease the resting tone.

Contracture –

Contracture is a condition of shortening and hardening of muscles, tendons, or other tissue, often leading to deformity and rigidity of joints. One way that contracture develops is due to nervous system disorders that cause an increase in tone. The increase tone puts the muscle in a shortened position which eventually causes it to loose its elasticity and the normal architecture of the muscle cells and connective tissue are replace with more inelastic connective tissue making the muscles hard to stretch preventing normal movement. Their can also be pain associated with contracture as well as decrease function. To “just want to tone” becomes even more of a troubling misunderstanding of the benefits of exercise when one considers that increase tone is a step on the way to contracture.

Recovery –

One of the goals of recovery modalities (see Part 2) is to decrease tone. To benefit from an exercise program, one must adapt to the exercise that is being done. This occurs by rebuilding and repairing the tissues used during the exercise so that they can perform more of the same type of exercise in the future. Recovery between workouts or exercise sessions is something that needs to be maximized to get the benefit of the exercise program. Maximizing recovery entails proper nutrition, proper sleep, proper hormone levels and normal levels of tone. Bringing the muscle tone back to normal after a training session signals the central nervous system that the stress is over and it can now release the rebuilding, repair or anabolic hormones. Normal tone in the muscles also allows the lymphatic and blood vessels to remove wastes and bring nutrients to promote the repairing and rebuilding process. Less tone is good for repair and recovery.

You keep using that word. I don’t think it means what you think it means.

Tone is not the opposite of hypertrophy.