Stretching and Flexibility

Stretching for Impaired Mobility

• Stretching is a therapeutic technique designed to increase the extensibility of soft tissues and improve flexibility, especially in structures that have adaptively shortened or become hypomobile

Flexibility

• Flexibility is the ability to move a single joint or a series of joints smoothly and easily through an unrestricted and pain-free range of motion (ROM).
• Muscle length, joint integrity, and the extensibility of soft tissues determine flexibility
• Flexibility depends on the ability of musculotendinous units to relax or deform and yield to a stretch force

Dynamic Flexibility

• Dynamic flexibility is the degree to which an active muscle contraction moves a body segment through the available ROM of a joint.
• Dynamic flexibility depends on muscle and soft tissue resistance

Passive Flexibility

• Passive flexibility is the extent to which a joint can be passively moved through its available ROM.
• Passive flexibility depends on the extensibility of muscles and connective tissues crossing and surrounding a joint

Hypomobility

• Hypomobility refers to decreased mobility or restricted motion.
• A wide range of pathological processes can restrict movement and impair mobility.
• Factors contributing to hypomobility include contractures, arthritis, joint injuries, connective tissue disorders, and fascia tension

Contracture

• Contracture involves the adaptive shortening of the muscle-tendon unit and other soft tissues that cross or surround a joint.
• Contractures lead to significant resistance to passive or active stretch and limitation of ROM, potentially compromising functional abilities
• Contractures can arise from various illnesses, pathological processes, and contributing factors

Contributing Factors to Contractures

• Prolonged immobilization
• Casts and splints
• Skeletal traction
• Intrinsic factors
• Pain
• Joint inflammation and effusion
• Muscle, tendon, or fascial disorders
• Skin disorders
• Bony block
• Vascular disorders
• Sedentary lifestyle
• Faulty or asymmetrical postures
• Paralysis
• Tonal abnormalities
• Muscle imbalances
• Postural malalignment (congenital or acquired)

Examples of Contractures

• Fractures
• Osteotomy
• Soft tissue trauma or repair
• Micro or macro trauma
• Degenerative diseases
• Joint diseases or trauma
• Myositis, tendonitis, fasciitis
• Burns
• Skin grafts
• Scleroderma
• Osteophytes
• Ankylosis
• Surgical fusion
• Confinement to bed or a wheelchair
• Neuromuscular disorders and diseases: CNS or PNS dysfunction
• Spasticity, rigidity, flaccidity, weakness, muscle guarding, spasm
• Scoliosis, kyphosis

Types of Contractures

• A physiotherapist must identify contractures for effective diagnosis
• Contractures are described by identifying the action of the shortened muscle
• Shortened elbow flexors preventing full elbow extension indicate an elbow flexion contracture

Contracture vs. Contraction

• A contraction describes the process of tension developing in a muscle during shortening or lengthening

Myostatic Contracture

• The musculotendinous unit adaptively shortens, causing a significant loss of ROM without specific muscle pathology.
• Myostatic contractures can be resolved through stretching.

Pseudomyostatic Contracture

• Limited ROM may result from hypertonicity, such as spasticity or rigidity, associated with a central nervous system lesion
• Conditions include cerebral vascular accident, spinal cord injury, or traumatic brain injury
• Muscles in a constant state of contraction lead to excessive resistance to passive stretch

Arthrogenic and Periarticular Contractures

• Result from intra-articular pathology
• Changes include adhesions, synovial proliferation, joint effusion, cartilage irregularities, or osteophyte formation
• Develop when connective tissues crossing or attaching to a joint or the joint capsule lose mobility, restricting normal arthrokinematic motion

Fibrotic and Irreversible Contracture

• Fibrous changes in muscle connective tissue and periarticular structures lead to adherence, causing fibrotic contractures.
• They involve permanent loss of soft tissue extensibility, irreversible by nonsurgical intervention. Normal muscle tissue and organized connective tissue are replaced with non-extensible, fibrotic adhesions and scar tissue.

Interventions for Soft Tissue Mobility

• Manual or Mechanical/Passive or Assisted Stretching
• External, end-range stretch force is applied in a sustained or intermittent manner, often with overpressure applied manually or via a mechanical device, elongates a shortened muscletendon unit and periarticular connective tissues, by moving a restricted joint just past the available ROM

Self-Stretching

• Any stretching exercise that a patient carries out independently after instruction and supervision by a therapist

Neuromuscular Facilitation & Inhibition Techniques

• Procedures designed to relax tension in shortened muscles reflexively prior to or during muscle elongation
• Inhibition techniques to assist with muscle elongation is related to proprioceptive neuromuscular facilitation (PNF)

Muscle Energy Techniques

• Voluntary muscle contractions by the patient occur in a controlled direction and intensity against a counterforce applied by the practitioner.
• Muscle Energy Techniques are also known as post isometric relaxation
• Muscle Energy Techniques are effective in lengthening and influencing the tonus of soft tissues and to treat muscle spasms

Joint Mobilization/Manipulation

• Manual therapy techniques are used to stretch capsular restrictions or reposition a subluxed or dislocated joint.
• Can release a blocked joint segment

Soft Tissue Mobilization and Manipulation

• Designed to improve muscle extensibility
• Involve application of specific and progressive manual forces (e.g. sustained manual pressure or slow, deep stroking)
• Changes the myofascial structures that can bind soft tissues and impair mobility

Soft Tissue Mobilization and Manipulation Techniques

• Friction massage
• Myofascial release
• Acupressure
• Trigger point therapy

Neural Tissue Mobilization

• After trauma or surgical procedures, adhesions or scar tissue may form around the meninges and nerve roots or at the site of injury at the plexus or peripheral nerves
• Tension placed on the adhesions or scar tissue leads to pain or neurological symptoms
• After tests to determine neural tissue mobility are conducted, the neural pathway is mobilized through selective procedures
• E.x. Neurodynamics, tests for neural tissue

Selective Stretching

• Selective stretching is a process whereby the overall function of a patient may be improved by applying stretching techniques selectively to some muscles and joints but allowing limitation of motion to develop in other muscles or joints
• For spinal cord injury patients use selective stretching, for example, trunk stability, is necessary for sitting independence

Selective Stretching for Thoracic and Cervical Lesions

• Individuals that lack active control of the back extensors
• If the hamstrings are routinely stretched to improve or maintain their extensibility and moderate hypomobility is allowed to develop in the extensors of the low back
• Enables a patient to lean into the slightly shortened structures and have trunk stability for long-term sitting

Overstretching & Hypermobility

• Overstretching is a stretch well beyond the normal length of muscle and ROM of a joint and the surrounding soft tissues resulting in hypermobility (excessive mobility)
• Selective hypermobility creation via overstretching can be useful for healthy athletes with normal strength and stability participating in sports that require extensive flexibility

Hypermobility

• Overstretching can be detrimental and creates joint instability when the supporting structures of a joint and the strength of the muscles around a joint are insufficient and cannot hold a joint in a stable, functional position during activities
• Unstable joints often cause pain and may increase a person's risk of musculoskeletal injury

Properties of Soft Tissue

• Response to Immobilization and Stretch:
  • Freely move the body and its parts without restrictions and with control during functional activities
  • Depend on the passive mobility of soft tissues and active neuromuscular control
  • Motion is necessary for the health of tissues in the body
  • Impaired mobility are the result of injury, disease, or surgery

Interventions Affect Soft Tissues

• Direction when procedures are applied to soft tissues
• Velocity when procedures are applied to soft tissues
• Intensity (magnitude) when procedures are applied to soft tissues
• Duration when procedures are applied to soft tissues
• Frequency of the stretch force tissue when procedures are applied to soft tissues
• Temperature when procedures are applied to soft tissues
• These factors affect the responses of the various types of soft tissue

Soft Tissue Interventions

• Biomechanical, biochemical, and neurophysiological responses of soft tissues to immobilization and remobilization have been derived from animal studies
• Knowledge of soft tissues and their responses to different interventions is an essential skill for the physiotherapist to make correct clinical decisions

Core Terms

• Elasticity is the ability of soft tissue to return to its prestretch resting length directly after a short-duration stretch force has been removed
• Viscoelasticity is a time-dependent property of soft tissue that initially resists deformation. For example, there is a change in length of the tissue when a stretch force is first applied
• Plasticity is the tendency of soft tissue to assume a new and greater length after the stretch force has been removed

Contractile and Noncontractile Tissues

• Tissues have elastic and plastic qualities
• Both contractile and noncontractile

Mechanical Properties of Contractile Tissue

• Muscle is composed of both contractile and noncontractile connective tissues
• Contractile elements of muscle give it the characteristics of contractility and irritability
• Noncontractile connective tissue in and around muscle resists all deformation

Types of Muscle Tissue

• Endomysium: the innermost layer that separates individual muscle fibers and myofibrils; connective tissue acting as a "harness" of a muscle
• Perimysium: encases fiber burrelles
• Epimysium: the enveloping fascial sheath around the entire muscle

Contractile Elements of Muscle

• Individual muscles are composed of many muscle fibers that lie in parallel with one another
• A single muscle fiber is made up of many myofibrils
• Each myofibril is composed of even smaller structures called sarcomeres, which lie in series within a myofibril

Sarcomere

• The contractile unit of the myofibril and is composed of overlapping myofilaments of actin and myosin that form cross-bridges
• Enable a muscle to contract and relax
• When a motor unit stimulates a muscle to contract, the actin-myosin filaments slide together, and the muscle actively shortens

Mechanical Response of the Contractile Unit to Stretch & Immobilization

• When a muscle is stretched and elongates, the stretch force is transmitted to the muscle fibers via connective tissue (endomysium and perimysium) in and around the fibers
• During passive stretch both longitudinal and lateral force transduction occurs

More on Mechanical Response

• Tension rises sharply and then there is mechanical disruption (influenced by neural and biochemical changes)
• Cross-bridges slide apart, leading to abrupt lengthening of the sarcomeres
• Stretch force is released, the individual sarcomeres return to their resting length

Response to Immobilization and Remobilization

• Morphological changes:
  • Physical stress on the muscle diminishes, when a muscle is immobilized -Decay of contractile protein -Decrease in muscle fiber diameter -Decrease in the number of myofibrils -Decrease in intramuscular capillary density -Muscle atrophy and weakness

Immobilization Response

• Increase in fibrous and fatty tissue
• Atrophy occurs quicker in tonic (slow-twitch) postural muscle fibers than in phasic (fast-twitch) fibers
• The longer the duration of immobilization, the greater is the atrophy of muscle and loss of functional strength

Implications of Immobilization

• Decrease in the cross-sectional size of muscle fibers over time
• Deterioration in motor unit recruitment occurs as reflected by electromyographic activity
• Both compromise the force-producing capabilities of the muscle

Immobilization in a Shortened Position

• Necessary after surgery, fracture, muscle tear, tendon rupture
• Results in a reduction in the length of the muscle and its fibers
• Reduction in the number of sarcomeres in series within myofibrils as the result of sarcomere absorption
• Decrease in the muscles capacity to produce maximum strength and tension

Immobilization in a Lengthened Position

• Application of a series of positional casts (serial casts)
• Dynamic splint to stretch a long-standing contracture and increase ROM
• Animal studies show an increase in sacromeres in a lengthened position. The timeline requirement is unknown

Neurophysiological Properties of Contractile Tissue

• Terms important for physiotherapists to know:
  • Muscle Spindle
  • Golgi Tendon

Muscle Spindle

• Main function is to receive and convey information about changes in the length of a muscle and the velocity of the length changes
• Spindles are small, encapsulated receptors composed of afferent sensory fiber endings, efferent motor fiber endings specialized muscle fibers called intrafusal fiber

Intrafusal and Extrafusal Fibers

• Intrafusal + extrafusal: Main Skeletal muscle
• Intrafusal fibers are innervated by gamma motor neurons, which innervate the contractile polar regions
• Extrafusal fibers are innervated by large-diameter alpha motor neurons

Types of Intrafusal Fibers

• Two types:
  • Nuclear bag fibres
  • Nuclear chain fibres
• Nuclei in the central portions of the fibers
• Primary (type Ia fiber) afferent endings, which arise from nuclear bag fibers, sense and cause muscle to respond to both quick and sustained (tonic) stretch
• Secondary (type II) afferents from the nuclear chain fibers are sensitive only to tonic stretch

Golgi Tendon Organ

• Sensory tendon organ located near the musculotendinous junctions of extrafusal muscle fibers
• Monitor changes in tension of muscle-tendon units
• Encapsulated nerve endings are woven among collagen strands of a tendon and transmit sensory information via Ib fibers

Golgi Tendon Organ Response

• When tension develops in a muscle
• GTO fires, inhibits alpha motorneuron activity
• Decrease tension in the muscle-tendon unit being stretched
• Inhibition is a state of decreased neuronal activity and altered synaptic potential, which reflexively diminishes the capacity of a muscle to contract

Golgi Tendon Organ Threshold

• Low threshold is present for firing in individuals which monitors and adjust the force of active muscle contractions during movement or during passive stretch

Neurophysiological Response to Stretch

• When a stretch force is applied to a muscle-tendon unit either quickly or over a prolonged period of time
• Primary and secondary afferents of intrafusal muscle fibers sense the length changes and activate extrafusal muscle fibers via alpha motor neurons in the spinal cord
• Activating the stretch reflex and increasing (facilitating) tension

Response Stretch Reflex

• When activated in a muscle being lengthened, the muscle on the opposite side of the joint has decreased activity. This known as reciprocal inhibition
• Stretching procedures are effective, because tensile stresses are placed on the non-contractile connective tissue in and around the muscle, leading to inhibition of the contractile elements of muscle