Connective Tissue

There are only four types of human tissue. We cover muscle and nerve tissue elsewhere and epithelial tissue, while being prolific throughout the body, is less relevant to our discussion. Connective tissue however is very relevant.

Function

In order for us to move, or even stand, a number of things have to happen.

• The nervous system triggers an electrical response in muscle tissue to contract.
• Chemical reactions in the muscle tissue release energy, either from stored glucose, or by processing oxygen molecules in the blood, which is converted onto movement by the contraction of muscle tissue.
• This movement generates a force that is transferred to the non-contractile connective tissue embedded in the muscle and continuous with the tendon and eventually the bones with which they attach.
• When this force overcomes whatever forces are keeping the bone stationary, it moves. When the bone moves we move.

So the fascia has two roles, it connects physically and it connects energically, facilitating the transformation of chemical energy stored in the muscle to the movement of the bone. (It has other functions too they are less relevant to this discussion.)

Structure

Connective tissue is made up, to varying degrees, of fibrous substances called collagen which gives it strength, and elastin which (surprise, surprise) adds elasticity to the tissue, embedded in a matrix of either fluid, solid or gel. The type of matrix and the relative mix of collagen and elastin reflects a phenomenon that exists throughout the body, that is the constant trade-off between strength and flexibility. Tissues rich in collagen tend to be thicker and less flexible but stronger while those with relatively less collagen are more flexible but can't take as much force as they would otherwise.

The structure of thefascia reflects this trade-off. Force is a product of magnitude and direction, the magnitude will determine the thickness of the fascia, that is the density of collagen fibres, while the direction of the force affects the arrangement of the fibres. Broad flat sheets of superficial fascia tend to have fewer collagen fibres that are arranged quite randomly while tendons are thicker and their fibres are mainly parallel, consistent with a more unidirectional force.

Collagen fibres provide tensile strength to the tissue. The forces applied to this tissue determine the density and arrangement of these collagen fibres.

Overuse

Connective tissue responds to the loads placed on it. When a muscle is overused the connective tissue component has more work to do so it lays down more collagen fibres in the direction that the forces are applied. This alignment however depends on the tissue being well hydrated, if it is not the collagen fibres will be laid down more randomly. When they are also densely packed in irregular patterns tendons become thick and inflexible.

Stretching and certain types of massage will encourage both hydration and tension along the line of force of the muscle, encouraging the more regular parallel alignment of collagen fibres required at healthy tendons.

The physiology of tendon injuries is not completely understood but it is now well accepted that both the density and arrangement of collagen fibres is an important factor. Refer to the section on Cumulative Trauma Disorders.

The Skeletal System

The Pectoral Girdle

The shaded area: the clavicle and scapula, is called the pectoral girdle. It's job is to support and articulate the upper limbs. The three joints of the pectoral girdle are the sternoclavicular joint where the clavicle articulates with (moves against) the sternum; the acromioclavicular joints where the clavicle articulates with the scapula (at the acromion process) and the glenohumeral joint, also called the shoulder joint, where the humerus fits into the glenoid fossa of the scapula.

The Upper Limb

The upper Limb consists of the humerus, the radius, the ulna and the bones of the numerous bones of the hand and wrist. It articulates with the pectoral girdle at the glenohumeral joint. The primary function of the arm and the shoulder is to place the hand in space. The shoulder moves the arm relative to the rest of the body while the elbow adds considerably to the range of motion of the hand, allowing us to take food to our mouths for one.

For more information on the arm and the spine refer to the relative sections in the biomechanics pages.

The Myofascia

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.

The Nervous System

The nervous and endocrine systems regulate the bodies functions, allowing it to maintain homeostasis, a state of balance. The nervous system is the control centre and can make fast changes while the endocrine system produces and secretes hormones that act more slowly. We are more concerned with the fast acting nervous system.

Nerves transmit electrochemical responses around the body and they do it real fast. The ways that these nerves are connected (here we go again) plays an important role in their function, especially in relation to movement. The connection between nerves in the brain, the spine and the limbs facilitates the transmission of data that controls how we determine our position in space and how we move to change that position. These specific pathways are in the main not predetermined but are developed throughout life. As we learn to catch a ball as a child we are creating neurological patterns that allow us to respond to our environment and move accordingly. We see the ball, we move, we catch it but we have to practice these things. In the practice we are establishing connections in our nervous system that trigger the appropriate sensory receptors and motor units (more about those soon). In the same way when learning to play a guitar we are establishing new connections in the nervous system that allow awkward stiff movements to evolve into automatic fluid ones.

muscle memory

The sensory motor system

Sensory organs perceive changes in our environment, or more accurately our relationship with our environment, and generate an electro-chemical impulse that is passed on to a sensory nerve and eventually to the brain for processing. Some specific types of impulses are intercepted and processed in the spine but they are by far the exception, we'll just say the brain to keep the language as simply as possible.

The brain then processes this input and spits out a signal along a motor nerve pathway that eventually reaches either a muscle or a gland. An action follows that changes our relationship with our environment, the sensory data regulates that change, we adjust motor activity where necessary and eventually reach again a point of equilibrium again.

Proprioception

The vast majority of sensory input is visual so we're used to getting our information this way. The convenient grid shape of the strings on the fretboard and the tendency to play in shapes and boxes within this grid make the guitar a very visual instrument. This tends to make us lazy, too many guitarists play to shapes rather than sounds, never bother to develop really good aural skills and get stuck playing the same old licks all the time because our fingers have memorised these shapes. This is not to mention of course the disastrous impact on our posture that is inevitable when we're looking down at the guitar all the time.

So, as sight-impaired people have learned to do, we need to develop other ways of getting information to our brain. Skeletal muscle is innervated not only by motor nerves but by sensory nerves as well. Proprioceptors gather information about muscle tension and send it north for processing. From this information the brain can determine the relative amounts of contraction and relaxation in various muscle groups and by extension exactly, more or less, where we are in space. When you close your eyes with arms outstretched and bring your finger in to touch your nose you're testing your proprioception.

Of course the only way to develop these skills, to establish the necessary neural pathways, is through practice. There are many technical exercises available for guitar players, those that have been developed for the TuneUp program look very specifically at developing proprioception and muscle memory. With each of them is a more detailed description of how they do it.

Stretching

The nervous system is crucial to our understanding of movement and biomechanics. As the quick-acting regulator it is the nervous system that instigates movement and regulates muscle tone. When you stretch a muscle you're not actually stretching the muscle tissue, you're adjusting the way that the nervous system controls muscle length. Over time this allows the actual fibres to lengthen by a process called creep.

Simple nerve endings in the myofascia called receptors give the brain information with which it can regulate muscle tone and determine your position in space.

Golgi Tendon Organs are located at the junction of the tendon and the main body of the muscle, excess tension here results in a signal to the brain to reduce the signal to the muscle to contract. The active stretching exercises and some of the massage techniques in the remedial program work because they activate the Golgi Tendon organs.

Muscle spindles, or stretch receptors, work the other way. If a muscle is being overstretched it is in danger of tearing and signals from muscle spindles tell the brain to increase tone to maintain the integrity of the muscle. If these receptors are over active they'll be telling the muscles to contract.The sort of physical relaxation that you experience from a good massage and from the exercises in the relaxation program probably works on reducing the activity of these muscle spindles.

Proprioceptors guage the tension in the myofascia. With the information from many different propriceptors you can determine the position in space of parts of your body. You can play without looking at your hands because you've done it enough times that your brain knows that the pattern it's getting from all the proprioceptors represents a certain position.

Connective tissue connects

Connective tissue is ubiquitous, you can't escape it. Fascia in particular weaves its way through the body embedded in muscles and lining bones and internal organs. Sheets of superficial fascia lie just beneath the skin, continuous with the web of deep fascia internal to it. Every time we move, and we're always moving, this fascia is under tension, transmitting forces from one part of the body to another. Here we will examine more closely the sequence of events that gets a sound out of you guitar.

Proprioceptors in your muscles inform your brain exactly where your hands and fingers are. Given that information your motor cortex initiates a firing sequence to take you from your current position to the guitar, let's just look at fretting one note for now. An elctro-chemical signal reaches your arm and generates contraction in the finger flexors and corresponding lengthening of the extensors along with contraction of muscles that stabilise the wrist.

Muscle fibres, each surrounded by a layer of fascia, are arranged roughly parallel with each other so that they all pull in the same direction. The fascial layers typically converge at the tendon at end of each muscle where the combined force of all the contracting muscle fibres is exerted at its attachment to the bone. The bone, itself comprised of connective tissue, is also encased in layers of fascia. The connective tissue from the muscle tendon effectively continues on until it covers the bone. Likewise the fascia surrounding the bone is embedded with the joint capsule providing yet another physical connection, this time to another bone.

So as the finger flexors contract tension is generated in the associated fascia which pulls on the inside of the phalanx (the bone in the finger). Because the extensors have relaxed tension on the opposite side of the finger is reduced and the bone moves around a pivot at the joint until the finger hits the fretboard. At this point touch and pressure sensors tell the brain that now would be a good time to reduce the contraction until there is just enough to keep the finger on the string.

So this simple movement creates tension in the fascia of the hand and the forearm. This fascia remember is not only in the tendons but throughout the muscle, lining the bones and in the joints as well. This isn't a problem when this tension is dissipated through movement but when it isn't, or when the fascia is overused, there will be consequences throughout the musculo-skeletal complex.

Biomechanics

Kinematics is the study of human movement

It's analysis examines the types of motions possible at particular joints and the muscles that make them possible. The guitarist needs to move and when he or she can obey the same rules as everyone else we'll be better off.

Biomechanics examines the various mechanical forces that the human body is subject to.

Force is defined by vectors that have both magnitude and direction. If we are examining for example the force required to play a downstroke then we can define a force vector whose direction is down in a straight line and magnitude is dependent on the tension of the string and the attack and volume required from the note.

Occasionally force vectors are more complex and require the combining of a number of component vectors. For example you hit a golf ball and it travels initially in a straight line in the direction that you hit it. Eventually however the force of gravity starts to bring it back down but not in a straight line. The combination of gravity and it's own momentum bring the ball down in an arc. If there is a cross-breeze then we have a third vector in the mix which takes the ball of the fairway all together. Fretting a note culminates in a resultant force directly down onto the fretboard but this apparently simple movement is merely the end result of forces that create tension in the arm, the hand and the finger, each with their own component vector.

The human skeleton is made up of series of levers, the muscles and connective tissue act as pulleys causing the skeleton to move. Each muscle crosses at least one joint with one bone, or lever arm, remaining still and the other moving around the joint in what we call a rotation movement, like the hands of a clock. The linear force produced by the muscle translates into a circular motion at the end of the mobile lever arm. Two types of forces are at play here. Firstly the muscle is pulling the two bones together, producing what we call a compression force at the joint, secondly because of the muscle attaches slightly distal to the joint it also wants to shear the two bones apart in a direction perpendicular to pure compression. The combination of these two forces produces the circular movement.

So while the skeleton moves and the muscles produce the force to make it happen it is the connective tissue that bears the loads. As two bones are being compressed together and sheared apart the connective tissue pulley needs to be strong enough to maintain the stability of the system. For this to happen it is under constant surveillance by the brain, becoming stronger and thicker the more it is used while getting weaker when it is used less in a process called creep. It's thought that when it doesn't have the chance to rest it doesn't self-repair and is subjected to repeated micro-traumas. This is why the term Cumulative Trauma Disorders is more accurate than overuse injuries although both are commonly used.

Understanding Kinematics and Biomechanics will offer the guitarist a number of advantages.

• By reducing mechanical loads we can reduce the amount of force required to move them.
• This will reduce the amount of energy required and therefore metabolic activity and biochemical waste.
• It will reduce the degree of strain on the connective tissue in particular, drastically reducing the likelihood of overuse injury.
• It will allow us to find postures and techniques that allow our hands easier, more fluent access to the instrument.
• It makes it possible to play with a greater degree of relaxation because we aren't working so hard.

Overuse Injuries

The term overuse injuries is descriptive and makes sense to the layperson which is why I've used it in the title. Medically it is an overused one however. Overuse injuries are a specific subset of what are now called Cumulative Trauma Disorders (CTD's), repeated low grade damage to muscle and connective tissue that never gets a chance to heal due to the constant use. Overuse injuries are characterised by repetitive movements where other CTD's are caused by both dynamic and static loading.

The likelihood of injury is greater when the forces involved increase and when the limbs are positioned in other than a neutral position. Biomechanical analysis then of the repetitive movements is vital in the long term resolution of these injuries.

Biomechanical loading is the result of forces produced both externally and internally through the contraction of muscle tissue, and are borne by collagenous connective tissue. They can occur at muscles, ligaments, tendons and bones, structures which all have strong connective tissue components. CTD's that affect the bone, such as shin splints, are uncommon in musicians while most soft tissue injuries tend to show damage to tendon, muscle and ligaments. Nerve tissue is also affected by CTD's.

Tendinopathies

Tendinopathy is the general term used to describe tendon injuries such as tendonitis, tendinosus and tenosynovitis. The muscle tendon is a strong fibrous tissue rich in collagen that conects the rest of the muscle usually to bone but sometimes to other tendons. These injuries used to be thought of as inflammatory conditions, similar to acute strains, but recent research, while not yet finding a solid alternative theory, has well and truly discounted this idea.

It is widely accepted however that problems with the collagen matrix in the connective tissue are related to tendinopathies. Some researches have proposed that it involves series of microscopic tears while others have added that the friction created by the debris from these disruptions causes further damage to the local tissue. The immediate results of cortisone injections with these injuries points to some indication of the collagen matrix and refutes the old infammation theories. It should be added that repeated cortisone injections can make tendons brittle and are ill-advised.

Tenosynovitis is a specific conditions affecting the synovium, a slippery connective tissue coating that helps to lubricate tendons in compact areas such as the wrist and hand.

Muscle injuries

Myofascial trigger points develop over time in hypertonic muscle tissue. The muscle develops localised areas of knotting that are hard, tender and sometimes cause pain elsewhere in the body. They tend to appear in well defined areas and refer pain to equally well defined regions. A common one in musicians is in the upper trapezius just below the ears on top of the shoulder.

Ischaemia is a state in which blood, and therefore oxygen, supply is reduced. It can be caused by damage to or inclusion (blockage) of blood vessels or in areas such as the supraspinatus tendon in the shoulder that are poorly vasculated. Ischaemic muscles tend to be painful when they contract. The pain is thought to be due to an increased build up of metabolites and/or the compression of pain receptors around dry, tight muscle fibres. Proponents of the trigger point theory suggest that long term ischaemia will lead to the development of trigger points. This idea is consistent with what I and most myofascial therapists see in clinic.

Muscle strain occurs when muscle fibres are torn, either in an acute unjury or over time. Muscle tears in CTD's are smaller, usually microscopic but still result in weakness, pain and and can lead to more serious problems such as those just described. Muscle strain due to postural loading is very common amongst musicians and guitarists are not immune to it. The many and varied postural approaches we tend to take, usually ruled by habit more than technique, tend to significantly exacerbate the problem.

Cramp is caused by contraction of shortened muscle and best relieved by stretching. It is exacerbated when muscles are fatigued and inflexible, dehydration and heat are also factors. Cramping in the left hand and forearm is common when we conitnue to play after the arm becomes fatigued. There are mountains of information in the program that deals with the causes of fatigue, inflexibilty and what to do about them.

Apart from these purely medical definitions the main problem is a general lack of conditioning brought on by the 21st century lifestyle. Our bodies have evolved to be hunters and gatherers, we're supposed to run for days, throw spears and wrestle tigers and most of us don't. We develop areas of weakness, tightness, some muscles are too short and others are too long and then we sit down for four hours hunched around a guitar, a bit silly really.

Ligament injuries

Most ligament injuries are relatively rare in musicians and tend to accompany tendon injuries, in which the treatment principles are the same: rest, reconditioning and rehabilitation of the offending activity.

Nerve injuries

Nerve injuries are not much fun, they tend to develop over time as with long term muscle hypertonicity either compressing nerves directly or causing postural changes that then result in compression by bony structures. Thoracic Outlet Syndrome is a condition that effects the nerves coming into the arm and is caused by compression between the scalene muscles in the neck and the first rib. Compression of the median nerve in the wrist will cause carpal tunnel syndrome. Radial, median and ulnar nerve entrapment are also caused by compression of muscles in the arm and a potential problem for musicians. If you suspect you may have one of these conditions get it checked out. The program will help with your rehabilitation but you need treatment.

What we know about CTD's

So while there are still lots of things that we don't know about Cumulative Trauma Disorders, and Overuse Injuries in particular, there are a few things that we do know.

• The likelihood of injury is greater when the forces involved increase and when the limbs are positioned in other than a neutral position.
• Muscles will shorten permanently when they are maintained in a short position for a length of time and to lengthen permanently when not being used over time in a phenomenon called creep.
• Tissues generally, muscle tissue, connective tissue and nerve tissue, suffer from hypertrophy from excessive use and atrophy from inadequate use.

Risk factors?

• Inadequate physical conditioning causes the sort of myofascial imbalances that are endemic in modern societies.
• Playing with excessive tension from stress, poor technique, postural imbalance, or simply not warming up will damage you body.
• Inadequate rehabilitation from previous injuries will compound new damage on top of old.

Treatment

Rest, Reconditioning and Rehabilitation of problematic activites.