The TuneUp Program

Myofascia is the soft tissue that generates and applies the force that holds our skeleton in position and moves it around. It is a more accurate term for what is usually referred to as the muscles.

myo - refers to the contractile component, the muscle fibres, the red stuff. These fibres shorten as a muscle contracts, supplying the motive force for the movement, but they are not strong enough to convey that force to other structures.

fascia - refers to the connective tissue component, it gives the muscle its tensile strength. Fascial sheets of varying thickness cover individual muscle fibres, groups of fibres and the muscle itself to eventually converge at either end of the muscle as tendons. These layers of fascia then continue to cover bones, joints and other muscles connecting a series of structures that work together to produce movement.

• The myofibril is the contractile element of the muscle cell, it shortens in response to an electrical stimulus.
• There are many myofibrils in a single fibre (cell) and many fibres in larger groups, called fascicles.
• Muscle fibres, fascicles and the muscle itself are all wrapped in sheets of fascia that converge at the tendons at either end of the muscle.
• These tendons then attach to the fascia that covers bones which in turn is continuous with other myofascial structures.
• The combined forces produced by contraction of the muscle fibres is applied, via these fascial sheets, to the tendon and eventually to a bone to produce movement.

Fascial tension

Fascia doesn't contract and nor does it readily stretch so forces applied to it will create tension. The fascial component of a contracting muscle is said to be under active tension. Because of the way that fascia connects and binds neighbouring structures active tension in one area will be transmitted to other connective tissue and called passive tension.

Contraction of the muscle fibre produces a force which creates tension in the local fascia and in structures with which it shares fascial connections.

There are important ramifications here for guitar players. Tension in one part of the body creates tension elsewhere. When muscles in the shoulder tighten up they pull on fascia that runs down the arm and to the hand. Apart from any postural or biomechanical considerations any passive tension in the arm will restrict movement and eventually change the physiology of tendons and muscles in the arm and hand (refer to the discussion of connective tissue).

Muscle fibres

Different muscles do different things and their fibres vary accordingly. Muscle fibres are essentially pretty simple - they turn on or they turn off. What varies is the speed at which this happens and the energy source that makes it happen.

Cells that contract quickly are called fast twitch fibres and those that contract slowly are called slow twitch fibres.

Cells that need energy fast can get it from glucose which is readily available in the muscle, they are called glycolitic (or white). The payoff is that it runs out relatively quickly so other fibres that can produce energy from oxygen (oxidative, or red), which is a slower more complicated process, then take over.

So the trade-off is between speed and endurance. Postural muscles that have to work a lot of the time have a higher percentage of slow twitch red fibres. Muscles responsible mainly for movement will have higher percentages of fast twitch white and fast twitch red fibres.

Guitarists must ask muscles in the hand and arm, designed for short bursts of energy, to work for longer. They fatigue, produce an excess of chemical waste due to the extra metabolic activity and their connective tissue make up changes. To remain healthy we need to manage this strain that our body is simply not designed for.

Muscle activity

Muscle fibres are specialised cells that have only one function, they contract. Groups of muscle fibres called motor units are each innervated by a single nerve cell whose sole function is to ilicit this contraction. When a nerve impulse reaches the motor unit every muscle fibre within it contracts to it's full capacity, when there is no signal each one lengthens to its resting state. The amount of force produced by a muscle depends on the number of motor units active at any one time.

If enough motor units activate a force will be generated that pulls one bone toward another. If there is no opposing force then the bones will move closer to each other and the muscle will shorten. If however the force of gravity or of another muscle produces a greater force in the opposite direction the muscle will actually lengthen even though individual motor units are generating a contractile force. The word contract is very misleading in this case as the fibres actually lengthen but it's so commonly used that we'll stick with it.

The section on biomechanics explains this in more detail, for now we have enough information to look at some important concepts and define some terms you may see throughout the program.

eccentric contraction	In which the muscle doesn't really contract at all but lengthens as the tendons at either end of it are seperated by a force greater than that being produced by the muscle. Eccentric contractions enable us to smoothly place a book on a table
concentric contractions	The muscle does actually shorten because it prduces enough force to draw the bones at either end of the tendon clser to each other.
isometric contractions	the muscle stays the same length because a force equal to that being produced by the muscle is pulling it in the opposite direction.
active insufficiency	If a muscle is chronically short it doesn't have far to contract so doesn't produce a lot of force. Actively insufficient muscle fibres use a lot of energy for the amount of work they can do so they will fatigue easily.
passive insufficiency	A significant counterforce that contracting muscles need to overcome is that produced by the tension in the connective tissue component of opposing muscles. When you bend to touch your toes and barely get past your knees it's because your hamstrings are so short that they generate a significant force when being stretched.
Golgi Tendon organs	Nerve receptors, located at the junction of the red contractile fibres and the tendon, that are sensitive to tension in the connective tissue. When this tension is high enough they send a message to the central nervous system to inhibit contraction thereby reducing the force produced by the muscle and the tension at the tendon.
Muscle spindles	Nerve receptors located within the connective tissue of the muscle body that can detect when the muscle is being overstretched. They then send a signal to the CNS that results in muscle contraction.