Developmental Essentials by IYCA, (04) Posture and Physical Development, Notes

Post date: Apr 23, 2016 1:55:57 PM

Developmental Essentials by IYCA

Chapter 4 - Development and flexibility - Theory

• 1. Study Questions

     1. Consider implications of hyper and hypo flexibility, short and long term consequences

     2. Athlete cannot maintain neutral spine during deep squats and lunges how might yoga help? How might it hinder?

     3. 10 major athletic movements and how hyper/hypo flexibility makes the moves dangerous

     4. Adverse effects of weak hypo flexible hamstring and flexible back.

     5. Compare and contrast dynamic and static flexibility

     6. Inherent problems with hyper flexibility and underdeveloped motor control

  2. Introduction

• • 1. Flexibility defined - ability to produce and reproduce efficient static and dynamic movements at desired speed over an optimal range of motion with proficient coordination of multi joint structures as they contract to an overall motion.

    2. Requires the seamless integration of multi joint agonists and antagonists, stabilizers, neutralizers and synergists a they actively generate movement.

    3. Joint specific characteristics

    4. Flexibility requirement of habitual movement (SAID)

• 3. Chief constituents of flexibility

• • 1. Up to 32 factors that contribute to flexibility in a given range of motion (structural, functional, varied)

       1. Structural means and limitations

          1. Joint structure, contractile and connective tissue composition, pennation angle (angle at which muscle inserts and fans out), insertion points, body fat (mechanical wedges, reduced range of motion), type of movement, environmental/tissue temperature

       2. Functional contributions stem from neuromuscular system

• • • • 1. Neurogenic contraction moderated by brain

        2. Un-involuntary reflex arcs moderated by golgi tendon organs, muscle spindles and joint mechanoreceptors

• • 1. 3. Other factors

• • • • 1. Age, gender ethnicity, pregnancy , training history and pain threshold

• • 2. Connective tissue - supports and binds other tissues together

• • • 1. Characterized by complex mixture of specialized structural and functional protein fibrils in large tissue specific 3D extracellular matrix - collagenous and elastic arranged in complex aggregating network. Gel like substance- acts as both lubricant and glue for protein fibrils.

      2. 3 general classifications

         1. Loose Connective

            1. most common - holds organs in place, attaches epithelial to underlying tissue

         2. Dense/fibrous

• • • • • 1. large amount of closely packed collagenous and elastic fibers

          2. high structural rigidity

          3. binds muscles to bones and bones to bones

          4. most essential in determining range of motions

          5. tendons, ligaments (aponeuroses) and deep fascia ( dermis and scars - stretching and flexibility

• • • 2. 3. Specialized

• • • • • 1. cartilage, bone, blood

• • • 3. Components

• • • • 1. collagen - inextensible fibrous protein produced by fibroblasts

           1. most abundant - ⅓ of all proteins en vivo

           2. primary component of living tissue

           3. 27 different types of collagen

              1. 80 to 90% consist of type I,II or III

                 1. type I - tensile strength of steel - molecular cables that strengthen tendons, ligaments, cartilage, fascia, bone and skin

                 2. type II - comprises 50-90% of collagen-found in hyaline - articular cartilage (structural strength)

        2. elastin - other major fibrous protein - glycoprotein

• • • • • 1. coils and recoils like a spring

          2. skin, blood vessels, heart, lungs, intestines, tendons and ligaments

          3. possess a great deal of elasticity

          4. conserves energy by use of recoil to return/maintain the form of sarcomere (base unit of muscle)

          5. helps disseminate isolated stresses

          6. assists in returning stretched organs back in shape

          7. helps protect bodily tissues by absorbing excessive forces

• • • • 3. ground substance (cement)

• • • • • 1. soluble, gel like polymer composed of a hydrated net of proteins

          2. mostly glycosaminoglycans link with core proteins to form proteoglycans

          3. spongy, cushion like qualities (shock absorbers)

          4. cartilage, intervertebral discs, skin

• • • • 4. water - 60 to 70% of connective tissue contents

• • • • • 1. attracted to tissues through osmosis

          2. causes swelling, creates turgor pressure (pressure of surrounding wall) in collagen net -- helps extracellular matrix to absorb external forces

          3. water combines with hyaluronic acid as principal connective tissue lubricant (prevents excessive cross linking (decreases extension of tissue, lowers impact on flexibility)

• • • 4. properties of connective tissue

• • • • 1. extensibility and elasticity - counter forces

        2. stretching is performed to augment extensibility

        3. dynamic flexibility is result of tissue elasticity and static flexibility (extensibility)

        4. strength of connective tissue has to do with maximum amount of stress it can withstand before experiencing plasticity (permanent change) --think severely sprained ankle (permanent joint instability)

        5. failure strength varies from tissue to tissue- lowers with injury, immobility and age

        6. viscoelastic - both elastic and viscous

        7. time and speed dependent characteristics

• • • 5. stress relaxation

• • • • 1. soft tissue stretched over a given distance over a long period of time reducing joint stability =

           1. fascia has a higher degree of stress relaxation than do tendons

        2. must be an optimal degree of mobility and stability (time compliance) for safe and adequate ROM and health

        3. creep - during long duration static stretch (5-20 minutes) quickly deforms and continues to lengthen over a finite period of time. 3 stages:

• • • • • 1. primary creep

             1. starts at rapid rate and slows over time

             2. strengthening of collagen crimp

             3. partial realignment of fibrils in extracellular matrix

             4. typically stops when total internal stress and external tensile ratios reach equilibrium

          2. 2nd stage

• • • • • • 1. connective tissues approach elastic limit but return to normal length after cessation load

• • • • • 3. 3rd Stage

• • • • • • 1. tissue experiences an excessive amount of external force during tertiary creep, the tissue separates, plastic deformation= permanent change in length and higher instability

• • • 6. connective Tissue Structures

• • • • 1. molecular level

           1. physiological composition of connective tissues determines overall extensibility and elasticity -- tissue cross section area and length provide the global restrictions on elongation

        2. fibril level

• • • • • 1. collagen - elastin ratio determines the extensibility and elasticity

             1. more collagen = more stiffness

          2. other factors

• • • • • • 1. fibril orientation and density

            2. collagen fiber maturity

            3. differences in ground substances

            4. level of hydration

            5. number of inter / intra fibril collagen crosslinks

• • • • • 3. tendons-attach muscles to bone-thick fibrous

• • • • • • 1. 86% of collagen is type I

            2. greatest tensile strength

            3. low viscoelasticity

            4. high shock absorbency - maintain collagenous crimp

            5. provide approximately 10% resistance movement

            6. higher number of collagenous crosslinks = less extensibility

            7. as tendon transitions to bone - unmineralised fibrocartilage to mineralized to bone

            8. as tendon merges with muscle collagen fibril insert into deep recesses - merge with actin fibers in the muscle sarcomere- creates shearing force greater than tensile (typical site for strain and injury)

            9. tendons have more elasticity (1% to 2%) that allows for storage and release of energy

• • • • • 4. ligaments

• • • • • • 1. bind bone to bone

            2. in some cases blend into joint capsule to form ligamentous sleeve

            3. function

               1. prevent dislocation

               2. stabilize joint

               3. limit excessive range of motion

               4. crisscross layering presents very little to no extensibility

               5. remain lax under normal unrestricted ranges of motion

               6. towards end ranes they grow taut

            4. should never be the focus of any flexibility /mobility program

• • • • • 5. fascia-fibrous sheet of connective material that binds muscles together at multiple levels

• • • • • • 1. elastic membranous sheets that present at different thicknesses and densities

            2. surrounds and protects structures of the boy

            3. lies in broad continuous and contiguous sheets

            4. major path for force conduction - myofascial force transmission

            5. organizes body through elaborate three dimensional webbing

            6. provides compartments for muscles and organs

            7. categories

               1. superficial - directly below dermis

               2. subserous - extra peritoneal

               3. deep fascia - 30% of muscle mass, 40% of resistance to stretching.

• • • 7. Chief Constituents of Flexibility: The contractile System

• • • • 1. Organizational hierarchy (fig. 4-5)

           1. encased by epimysium - fascicles (smaller units)

           2. fascicles (1,000’s) of very long, cylindrical cells myofibers (muscle fibers) enclosed by perimysium

           3. fascicles lie parallel to one another, forming belly of the muscle

           4. broken down into repeating contractile units known as sarcomeres

           5. extensibility of skeletal muscle is directly proportional to its length and thus its number of sarcomeres in series

        2. Reflexive Considerations

• • • • • 1. Central Nervous System

             1. spinal cord and brain - regulates sensitivity of feedback coming from periphery, storing and formulating movement plans

                1. coordination center

                2. involuntary reflexes

          2. Peripheral Nervous System

• • • • • • 1. sensory neurons (afferent) signals go from mechanoreceptors to central nervous system

            2. motor neurons run from central nervous system to muscle fibers

• • • • • 3. Nerve Cell

• • • • • • 1. Axon - long process of nerve fiber

            2. conducts impulses away from the body of a nerve cell

            3. extends from cell body to muscle - branches out at motor end plate of muscle

            4. motor unit

               1. alpha motor neuron plus muscle complex

                  1. size determines control

                  2. eye muscles = 6 units (small, finely coordinated)

                  3. quadriceps = up to 2,000 muscle fibers (large movement)

            5. receptors (afferents) - involved in process of proprioceptive control

• • • • • • • 1. controls movement through range of motion

              2. paramount for dynamic flexibility

              3. mechanoreceptors - responsible for proprioception

                 1. golgi tendon organs - read tension in tendons

                 2. muscle spindles - read change and rate of change in muscle fiber

                 3. joint or articular sense

                 4. joint position

                 5. amplitude

                 6. acceleration

                 7. velocity of motion

                 8. joint stresses and pressures

                 9. pain and irritation

• • • • • • 6. Spindles - highly sensitive stretch receptors located in the muscle. Each spindle has ten intrafusal fibers encapsulated in connective tissue. Attach to endomysium of extrafusal (contractile fibers (run parallel). There are two types. Nervous System gets information on both amount and speed of lengthening muscles

• • • • • • • 1. nuclear bag fibers - non contractile sac-like structure in equator region (abundance of sarcoplasm and cell nuclei)

                 1. polar ends = striated contractile (attach endomysium of extrafusal fibers.)

              2. Nuclear chain fibers - thinner and shorter (attached to nuclear bag fibers. Sensitivity of reception is determined by extrafusal fibers (signals from central nervous system to fibers) = motor unit

              3. gamma motor neuron (gamma efferent) innervate equator region (conduct signal from central nervous system to intrafusal fibers

              4. motor axons

• • • • • • • • 1. static gamma axon - increase length sensitivity of primary sensory neurons - persistent static response without significant concurrent influence of dynamic response.

                2. dynamic gamma axon - increase velocity sensitivity of primary sensory neurons - dynamic response of muscle spindle (minimal static response)

• • • • • • • 5. Primary Endings - are type Ia afferents. annulospiral endings around center of nuclear bag fibers. Form side branches of nuclear chain fibers. Easily excited (low stretch threshold - phasic and tonic response to elongations - provides feedback on length of muscle

              6. Secondary endings (type II afferents) branch type endings - near equator of nuclear chain fibers. Work in unison with primary endings) send information regarding fibril length to central nervous systems during stretch

• • • • • • 7. golgi tendon organs (page 110) - contraction sensitive mechanoreceptors - located on aponeuroses of the musculotendinous junction

• • • • • • • 1. function is to protect muscles, tendons and ligaments from injury

              2. located directly in line of force between muscle and bone

              3. low threshold

              4. dynamic sensibility

              5. capable of small repetitive contraction

              6. one golgi tendon organ can use from 3 up to 50 intrafusal muscle fibers

              7. golgi tendon organ is encapsulated by muscle fiber

              8. innervated by type 1b afferent nerve fiber

                 1. large diameter

                 2. fast conduction

              9. tendon organ straightens collagen tissues when muscle contracts to produce tension in musculotendinous junction

              10. compression of nerve ending causes it to fire, sending signals through spine to central nervous system

• • • • • • • • 1. rate of change in tension

                2. most sensitive to muscular contraction

• • • • • • 8. Articular Mechanoreceptors - four types classified by morphology and behavior of nerve endings, located in all synovial joints

• • • • • • • 1. Type 1 - thinly encapsulated globular corpuscles located in exterior fibrous joint capsules

                 1. slow adapting

                 2. low threshold to stress

                 3. respond to small mechanical stress

                 4. function is to signal direction, amplitude and velocity of active and passive movement via regulation of joint pressure change

                 5. active at all times and fires impulse entire time that they are placed under stress

              2. Type II - conical corpuscles - larger and thicker, located deep in fibrous joint capsule

• • • • • • • • 1. dynamic velocity dependent firing

                2. do not fire during immobility or rest

• • • • • • • 3. Type III - exist in and outside joint capsule

• • • • • • • • 1. high threshold, slow adapting

                2. monitor direction of movement (inactive in immobile joints)

                3. active during extreme ranges of motion

                4. offers reflexive braking to avoid overstress in joints

• • • • • • • 4. Type IV - nociceptors -

• • • • • • • • 1. pain receptor system of articular cartilage

                2. nonencapsulated

                3. active when articular tissues are subject to mechanical deformation or chemical irritation

                4. Two types:

                5. IVa - lattice-like in joint fat pads (not in synovial tissue)

                6. IVb - free nerve endings - in intrinsic and extrinsic ligaments of the joint capsule

• • • • • • 9. Reflex Arcs - Reflex unconscious response to stimuli

• • • • • • • 1. involve functional mechanoreceptors, central nervous system and spinal cord

              2. although movement is involuntary, subject to control from higher centers

              3. myotatic stretch reflex - maintains optimal operating range of length in muscle

                 1. mediated by muscle spindles

              4. Reciprocal innervation - cross extensor reflex

• • • • • • • • 1. orchestrates the contraction and relaxation process for oppositional muscles, contraction relaxation cycles

                2. necessary for movement

• • • • • • • 5. coactivation - both agonist and antagonist muscles active

              6. autogenic inhibition - inverse stretch reflex

• • • • • • • • 1. yielding of muscle stretch reflex during static stretch

• • • • • • 10. active and passive resistance to stretch

• • • • • • • 1. passive tension - parallel elastic component

                 1. in vitro - outside body

                 2. contributes to storage of elastic energy (lengthened state)

• • • • • • 11. Series Elastic Component - elastic elements that lie in direct line with contractile component