Ch_5_ FlexibilityLow-BackHealthPart1F2023.pptx

CHAPTER 5 Flexibility and LowBack Health Part 1 © 2022 McGraw Hill Limited Learning Objectives LO1: List the factors that affect a joint's flexibility. LO2: Identify the potential benefits of flexibility and stretching exercises. LO3: Describe the intensity, duration, and frequency of stretching e...

CHAPTER 5 Flexibility and LowBack Health Part 1 © 2022 McGraw Hill Limited Learning Objectives LO1: List the factors that affect a joint's flexibility. LO2: Identify the potential benefits of flexibility and stretching exercises. LO3: Describe the intensity, duration, and frequency of stretching exercises that will develop the most flexibility with the lowest risk of injury. LO4: Describe the different types of stretching exercises and how they affect muscles. LO5: List safe stretching exercises for major joints. LO6: Explain how low-back pain can be prevented and managed. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 2 5.1 What Determines Flexibility? (LO1) Flexibility • is the ability of a joint to move through its full range of motion (ROM). • is important for general fitness & wellness. • is an often neglected component of health-related fitness. • is a highly adaptable physical fitness component. • increases in response to a regular program of stretching exercises. • is specific to the joint. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 3 What Determines Flexibility? Static Flexibility • The ability to hold an extended position at one end or point in a joint’s ROM. Dynamic Flexibility • The ability to move a joint through its ROM with little resistance Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 4 What Determines Flexibility? Factors that Affect Static and Dynamic Flexibility Static Flexibility Dynamic Flexibility • Stretch tolerance • Static flexibility • Joint structure • Strength • Tightness of muscles • Coordination • Tightness of tendons • Resistance to movement • Tightness of ligaments Fit & Well: Chapter 5      Joint capsule Muscle & its fascia Tendons Ligaments Skin © 2022 McGraw Hill Limited 5 What Determines Flexibility? • Joint Structure  Primary determinant. • Muscle Elasticity & Length • Nervous System Regulation Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 6 What Determines Flexibility? Joint Structure • The amount of flexibility in a joint is determined in part by the nature & structure of the joint. • Hinge Joints  Have 1 axis of rotation.  Allow flexion & extension at the joint.  Examples: Knee, elbow, ankle, & finger. • Ball and Socket Joints  Have 3 axes of rotation.  Allow flexion, extension, abduction, adduction, circumduction, & rotation at the joint.  Examples: Hip & shoulder. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 7 What Determines Flexibility? Joint Structure • Major Joints  Surrounded capsules. by FIGURE 5.1 Basic joint structure. joint • Joint Capsules  Semi-elastic structures, composed primarily of connective tissue, that give joints strength & stability, but limit movement. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 8 What Determines Flexibility? Joint Structure • Heredity & Gender  Play a part in joint structure & flexibility. • Gender  Generally, females are more flexible than males at all ages.  However, at the same age: o females have greater hip flexion & lateral spinal flexion than males. o males have greater hip extension, spinal flexion, & spinal extension than females. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 9 What Determines Flexibility? Muscle Elasticity & Length What is the key to developing flexibility? A) Skin tissue B) Tendon tissue C) Muscle tissue D) Ligament tissue Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 10 What Determines Flexibility? Muscle Elasticity & Length • The most important component of muscle tissue related to flexibility is the connective tissue that surrounds & envelops every part of the muscle tissue. • Connective Tissue  Provides structure, elasticity, & bulk to muscle tissue.  makes up about 30% of muscle mass. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 11 What Determines Flexibility? Muscle Elasticity & Length Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 12 What Determines Flexibility? Muscle Elasticity & Length • 2 Principal Types of Connective Tissue in Muscle  Collagen: white fibres that provide structure & support in connective tissue.  Elastin: yellow fibres that are elastic making connective tissue flexible. • An Important Structural Protein in Muscle  Titin o is a filament in skeletal muscle that helps align proteins that cause muscle contraction. o has elastic properties & contributes to flexibility. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 13 What Determines Flexibility? Muscle Elasticity & Length • Elastic Elongation  Temporary change in the length of muscles, tendons, and supporting connective tissues when a muscle is stretched. • Plastic Elongation  Long-term change in the length of muscles, tendons, and supporting connective tissues when a muscle is stretched regularly.  Without regular stretching, plastic elongation is reversed and the tissues shorten, which results in decreased flexibility. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 14 What Determines Flexibility? Muscle Elasticity & Length • Regular Stretching  May contribute to flexibility by lengthening muscle fibres through the addition of contractile units called sarcomeres. • Sarcomeres  The contractile units of a myofibril.  Repeating units along the length of a myofibril, occupying the region between Z lines of the myofibril.  Striped in appearance as a result of the overlapping of thin & thick contractile myofilaments called actin & myosin, respectively. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 15 What Determines Flexibility? Muscle Elasticity & Length • Research has shown that flexibility is improved best by stretching when muscles are warm & the stretch is applied gradually & conservatively. • Sudden, high-stress stretching is less effective & can lead to muscle damage. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 16 What Determines Flexibility? Nervous System Regulation • Proprioception  Means “sense of self.”  The unconscious perception of movement & spatial orientation arising from stimuli within the body itself.  The sense that deals with sensations of body position, posture, balance, & motion.  Perception mediated by proprioceptors or proprioceptive tissues. • Proprioceptors  The sensory nerve receptors situated in the muscles, tendons, & joints that furnish information to the central nervous system concerning the movements & positions of the limbs, trunk, head, & neck. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 17 What Determines Flexibility? Nervous System Regulation • Proprioceptors Involved in Stretching  Muscle Spindle o is a small sensory receptor or organ, located in the belly of the muscle, that monitors (senses) changes in muscle length.  Golgi Tendon Organ o is a small sensory receptor or organ, located at the junction between a muscle & its tendon, that monitors (senses) muscle tension. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 18 What Determines Flexibility? Important Definitions for Nervous System Regulation • Reflex: a predictable, involuntary response to a stimulus. • Spinal Reflex: is carried out by neurons (nerve cells) in the spinal cord alone & does not involve the brain. • Alpha Motor Neuron: a motor nerve cell in the spinal cord that leaves the central nervous system (CNS) to establish a functional connection with an effector, a skeletal muscle cell (fibre), and it sends signals to muscle fibres, making them contract. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 19 What Determines Flexibility? Important Definitions for Nervous System Regulation • Afferent Nerve Fiber: conveys (carries) nerve impulses (signals) from the periphery to the CNS (spinal cord & brain).  Example: Ia afferents of skeletal muscle spindles carry impulses to the spinal cord. • Efferent Nerve Fiber: conveys nerve impulses from the CNS to the periphery.  Example: The nerve fibres of an alpha motor neuron carry impulses from the CNS to their skeletal muscle fibres. • Agonist: a muscle whose contraction opposes the action of another muscle, its antagonist, which relaxes at the same time.  Example: The biceps muscle contracts while its antagonist, the triceps muscle, relaxes. • Antagonist: a muscle that opposes or resists the action of its agonist. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 20 What Determines Flexibility? Nervous System Regulation • Muscle Spindles  are composed of miniature specialized muscle fibres called intrafusal fibres that run parallel to the skeletal muscle fibres.  are sensitive to both the amount & rate of the change in skeletal muscle length.  provide information about the length of skeletal muscle.  control the length of skeletal muscle.  when stimulated, initiate the Stretch Reflex. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 21 What Determines Flexibility? Nervous System Regulation: Muscle Spindles and the Stretch Reflex 3 2 4 Stretch Reflex Relieves the stretching of muscle & prevents muscle damage from overstretching. 1 5 Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 22 What Determines Flexibility? Muscle Spindles and the Stretch Reflex • When a muscle is stretched (lengthened):  The muscle spindles are stimulated & send an electrical signal to the spinal cord through their afferent nerve fibres, called the Ia afferent nerve fibres.  The electrical signal arriving in the spinal cord is transformed into a chemical signal that is eventually converted back into an electrical signal that is sent to the same muscle by way of the alpha motor neuron.  The electrical signal that travels down the alpha motor neuron triggers a concentric muscle contraction that resists the change in muscle length.  While one muscle, the agonist, is being activated, the opposing muscle, the antagonist, is relaxing, which further facilitates the contraction of the muscle that was being stretched. • Example  A rapid stretching of the biceps brachii (agonist) muscle will result in a concentric muscle action (shortening) in the biceps brachii muscle & relaxation in the triceps brachii (antagonist) muscle. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 23 What Determines Flexibility? Nervous System Regulation • Golgi Tendon Organs  are located in series with skeletal muscle fibres.  are activated by muscular contractions that stretch the tendons.  monitor all degrees of muscle tension, but they are most sensitive to tension generated by muscle contraction.  provide information about the tension in skeletal muscle.  when stimulated, initiate the Inverse Stretch Reflex, which is also called the Inverse Myotatic Reflex. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 24 What Determines Flexibility? Nervous System Regulation • Golgi Tendon Organs  are composed of small bundles of tendon fibres enclosed in a layered capsule with dendrites (fine branches of neurons) coiling between & around the fibres. (Source: Purves et al., Neuroscience, 2nd Ed., 2001.) Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 25 What Determines Flexibility? Nervous System Regulation • Golgi Tendon Organs and the Inverse Stretch Reflex  Inverse Stretch Reflex protects muscles & their corresponding muscles from the damage that could result from excessive tension. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 26 What Determines Flexibility? Golgi Tendon Organs and the Inverse Stretch Reflex • When a muscle performs a concentric muscle action (shortens):  The GTOs are stimulated & send an electrical signal to the spinal cord through their afferent nerve fibres, called the Ib afferent nerve fibres.  The electrical signal arriving in the spinal cord is transformed into a chemical signal that activates an inhibitory interneuron.  The electrical signal from the inhibitory interneuron results in the release of another chemical signal that inhibits the efferent nerve cell, the alpha motor neuron.  Consequently, the muscle that was experiencing the increase in muscle tension will relax. • Example  The biceps brachii muscle is performing a concentric muscle action, which activates the GTOs resulting in a reflexive relaxation in the biceps brachii muscle. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 27 What Determines Flexibility? Functional Comparison of Muscle Spindles and Golgi Tendon Organs MUSCLE PASSIVELY STRETCHED MUSCLE ACTIVELY CONTRACTED (Source: Purves et al., Neuroscience, 2nd Ed., 2001.) Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 28 What Determines Flexibility? Summary of the Muscle Spindles and Golgi Tendon Organs Variable Location Muscle Spindles Golgi Tendon Organs Belly of the muscle Myotendinous junction Parallel Series Sense, Monitor, or Detect Muscle length Muscle tension Muscle Response Reflexive muscle action Afferent Never Fibre Ia afferent Ib afferent Efferent Nerve Fibre Alpha motor neuron Alpha motor neuron Activated Reflex Stretch reflex Inverse stretch reflex Location Relative to the Skeletal Muscle Fibres Fit & Well: Chapter 5 © 2022 McGraw Hill Limited Reflexive muscle relaxation 29 5.2 Benefits of Flexibility (LO2) • Good Flexibility  Provides benefits for the entire musculoskeletal system. • Flexibility Training      Increases ROM. May prevent muscle strains. Increases strength & quality of movement. Might decrease the risk of some sports injuries. Does not prevent overuse injuries. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 30 Benefits of Flexibility • Joint Health • Prevention of Low-Back Pain & Injuries • Additional Potential Benefits Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 31 Benefits of Flexibility Joint Health • Good Flexibility  Essential to good joint health.  Prevents joint deterioration caused by the tightness of soft tissues such as muscles & other tissues.  Prevents abnormalities in joint lubrication caused by poor joint flexibility.  May prevent arthritis.  Increases balance & stability in older adults. • Lack of Exercise  Which tends to occur as people age, decreases flexibility. • Age  Decreases the natural elasticity of muscles, tendons, & joints, resulting in stiffness. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 32 Benefits of Flexibility Prevention of Low-Back Pain • Low-Back Pain  Can be related to muscle imbalances resulting in poor spinal alignment.  Most commonly caused by muscle imbalances between the abdominals & posterior spinal muscles.  May be prevented by strength & flexibility in the back, pelvis, & thighs. • Research Studies  Research studies have not yet clearly defined the relationship between back pain & lack of flexibility.  Few studies have found that trunk flexibility improves back health or reduces the risk of injury.  Some studies show that poor flexibility does increase one’s risk for injury. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 33 Benefits of Flexibility Prevention of Low-Back Pain • People with either high or low flexibility seem to have an increased risk for injury.  Extreme flexibility reduces joint stability.  Poor flexibility limits a joint’s range of motion. • Stretching programs are particularly important for:     Older adults. High-power sports that include rapid changes in direction. Workers involved in brief bouts of intense exertion. People who sit for prolonged periods. • Static stretching  Before a high-intensity activity may increase the risk of injury interfering with neuromuscular control & reducing the natural ability of muscles to stretch and contract. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 34 Benefits of Flexibility Additional Potential Benefits • • • • • Relief of aches & pains. Relief of muscle cramps. Improved body position & strength for sports & life. Maintenance of good posture & balance. Relaxation  Flexibility exercises reduce mental tension, decrease the breathing rate, & reduce blood pressure. • Improving impaired mobility. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 35 Benefits of Flexibility Current Flexibility Training Research • Flexibility Training  Improves the range of motion (ROM) of the muscle being stretched, but it can also increase the ROM in non-stretched muscles in other parts of the body. • Examples • Unilateral stretching of the quadriceps will improve the ROM of the contralateral quadriceps (Chaouachi et al., 2017). • Stretching of the hip adductor (groin) muscles can improve the flexibility of the shoulders (Behm et al., 2016). • Stretching improve the flexibility hamstrings Chaouachi A, Padulo J, the Kasmishoulders S, Othmen AB,can Chatra M, Behm DG. Unilateral static of andthe dynamic hamstrings stretching increases hip flexion range of motion. Clin Physiol Funct Imaging. 37(1): 23-29, 2017. (Behm et al.,contralateral 2016). doi: 10.1111/cpf.12263. Behm DG, Cavanaugh T, Quigley P, Reid JC, Nardi PS, Marchetti PH. Acute bouts of upper and lower body static and dynamic stretching increase non-local joint range of motion. Eur J Appl Physiol. 116(1): 241-9, 2016. doi: Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 36 10.1007/s00421-015-3270-1. Assessing Flexibility • Flexibility  is specific to each joint, which is why tests of general flexibility do not exist. • Static Flexibility  Assessed in field & clinical settings.  Tests measure ROM directly & indirectly.  Easier to measure & better researched than dynamic flexibility. • Dynamic Flexibility  Testing is limited to the research setting.  Tests measure the increase in resistance during the lengthening of skeletal muscle.  Testing is more costly than static flexibility because of the use of expensive equipment. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 37 Methods of Assessing Static Flexibility • Direct Methods  Goniometer  Flexometer • Indirect Methods  Sit-and-Reach Tests  Skin Distraction Test  Inclinometer Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 38 Directs Methods of Assessing Static Flexibility Goniometer • is a protractor-like device with 2 steel or plastic arms that measures the ROM as the difference between the joint angles in units of degrees at the extremes of the ROM. Example: measuring the ROM at the knee joint. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 39 Directs Methods of Assessing Static Flexibility Flexometer • is a device composed of a weighted 360 degree dial & weighted pointer that measures the ROM for a given joint in relation to the downward pull of gravity on the dial & pointer. Example: measuring the ROM at the elbow joint. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 40 Directs Methods of Assessing Static Flexibility Inclinometer • is another type of gravity-dependent goniometer that measures the angle between the long axis of the moving segment & the line of gravity. Example: double inclinometer technique used to measure low back flexibility (lumbosacral flexion). Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 41 Directs Methods of Assessing Static Flexibility A goniometer, flexometer, or other instrument to measure ROM can be used to assess static flexibility in the following joints: • Shoulder  Abduction & Adduction  Flexion & Extension • Wrist  Flexion & Extension • Trunk / Low Back  Lateral Flexion • Hip  Flexion (Bent Knee or Straight Leg) & Extension  Abduction & Adduction  Medial & Lateral Rotation • Knee  Flexion & Extension • Ankle  Dorsiflexion & Plantar Flexion Refer to Lab 5.1 on pages 229 to 236 of the current course textbook. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 42 Key Flexibility Terms • Abduction: movement away from the midline of the body. • Adduction: movement toward the midline of the body. • Flexion: bending; bringing 2 bones together; reducing the angle at a joint.  Exception: flexion at the shoulder joint. • Extension: straightening; moving bones apart; increasing the angle at a joint.  Exception: extension at the shoulder joint. • Medial Rotation: rotation of a limb toward the midline of the body. • Lateral Rotation: rotation of a limb away from the midline of the body. • Dorsiflexion: flexion only at the ankle joint (bringing the toes towards the shin bone). • Plantar Flexion: extension only at the ankle joint (pointing the foot downwards). • Circumduction: circular movements at a joint. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 43 Examples of Key Flexibility Terms Shoulder Joint Abduction Adduction Flexion Circumduction Lateral Rotation Extension Medial Rotation Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 44 Examples of Key Flexibility Terms Spinal Joint Elbow Joint Ankle Joint Flexion Dorsiflexion Plantar flexion Extension Lateral Flexion Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 45 Indirect Methods of Assessing Static Flexibility Sit-and-Reach Test • The most commonly used flexibility test. • Provides an indirect, linear measurement of the ROM. • Included in most health-related fitness test batteries. • Used to evaluate the static flexibility of the lower back & hamstring muscles. • According to recent research, is not a valid measure of low back & hamstring flexibility. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 46 Sit-and-Reach Test • Warm-Up  First, perform a low-intensity activity such as walking or easy jogging.  Then perform slow stretching movements. • Performance of the Test  Remove your shoes.  Sit facing the flexibility measuring device with your knees fully extended & your feet flat against the device 10 cm apart.  On an exhale, reach as far forward as possible with the palms down, arms evenly stretched, & knees fully extended.  Hold this position for about 2 seconds. Lab 5.1 - Footline is set at 26 cm. Fit & Well: Chapter 5  Perform the test a second time.  Record both trials of the test to the nearest 0.5 cm.  Select the best score & rate your flexibility score by referring to the table of norms on slide 47 or page 230 of the current course textbook. © 2022 McGraw Hill Limited 47 Ratings for the Sit–and–Reach Test Men Age Needs Improvement Fair Good Very Good Excellent 15-19 20-29 30-39 40-49 50-59 60-69 ≤ 23 ≤ 24 ≤ 22 ≤ 17 ≤ 15 ≤ 14 24 – 28 25 – 29 23 – 27 18 – 23 16 – 23 15 – 19 29 – 33 30 – 33 28 – 32 24 – 28 24 – 27 20 – 24 34 – 38 34 – 39 33 – 37 29 – 34 28 – 34 25 – 32 ≥ 39 ≥ 40 ≥ 38 ≥ 35 ≥ 35 ≥ 33 Women Age Needs Improvement Fair Good Very Good Excellent 15-19 20-29 30-39 40-49 50-59 60-69 ≤ 28 ≤ 27 ≤ 26 ≤ 24 ≤ 24 ≤ 22 29 – 33 28 – 32 27 – 31 25 – 29 25 – 29 23 – 26 34 – 37 33 – 36 32 – 35 30 – 33 30 – 32 27 – 30 38 – 42 37 – 40 36 – 40 34 – 37 33 – 38 31 – 34 ≥ 43 ≥ 41 ≥ 41 ≥ 38 ≥ 39 ≥ 35 Fit & Well: Chapter 5 © 2022 McGraw Hill Limited SOURCE: Table: Ratings for Sitand-Reach Test. Canadian Society for Exercise Physiology – Physical Activity Training for Health (CSEPPATH®), © 2013. Scores are in cm.* *Footline is set at 26 cm. 48 Skin Distraction Test Midline of lumbar spine. 15-cm mark 0-cm mark Assesses low back flexibility. Fit & Well: Chapter 5 © 2022 McGraw Hill Limited 49