p.28
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is viscosity?
The resistance to an external force that causes permanent deformation.
p.34
Exercise-Induced Muscle Injury and Recovery
What occurs in the failure range of tissue?
The stress increase continues until the tissue ruptures.
p.3
Types of Muscle Tissue: Skeletal, Smooth, Cardiac
What are the characteristics of skeletal muscle?
Voluntary, striated, and multinucleated.
p.42
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the relationship between muscle tension and its length?
The amount of tension produced by a muscle is related to its length.
p.42
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the resting length of a muscle?
The length at which the maximum number of actin-myosin crossbridges is available.
p.46
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What factors influence the amount of active tension a muscle can generate?
Neural factors and mechanical properties.
p.26
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is an agonist in muscle movement?
Any contracting muscle that causes the same joint motion or maintains a posture.
p.32
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the elastic region in tissue?
The point at which the tissue’s elastic properties are stressed.
p.26
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What are prime movers?
Muscles that contribute significantly more to the joint movement than other agonists.
p.12
Muscle Contraction Mechanism: Sliding Filament Theory
What role does calcium play in ATPase activity?
Calcium stimulates myosin to act as a catalyst to split ATP.
p.16
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is a motor unit?
The functional unit of muscle contraction, including the alpha motor nerve and all the muscle fibers it innervates.
p.48
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What occurs during eccentric contraction followed by concentric contraction of the same muscle?
The total force generated is greater than during isolated concentric contraction.
p.21
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is Henneman’s size principle?
The order of recruitment from smaller to larger alpha motor neurons.
p.59
Effects of Immobilization on Muscle Structure and Function
What happens to muscles immobilized in a lengthened position compared to those in a shortened position?
They exhibit fewer structural and functional changes.
p.2
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
Define extensibility in the context of muscle properties.
A muscle can be stretched beyond its normal resting length and still be able to contract.
p.48
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the basis for plyometric training?
The integration of eccentric and concentric contractions that utilize stored elastic energy.
p.51
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is passive insufficiency?
A condition where a muscle limits the ability of its opposing muscle to contract due to lengthening.
p.54
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How can the strength of finger flexors be maintained?
By lengthening the muscle at another joint, such as extending the wrist.
p.54
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What effect does wrist extension have on finger flexors?
It allows the finger flexors to have enough length to provide a strong grip.
p.16
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What factors can alter the magnitude of muscle contraction?
The number of motor units activated and the frequency at which they are activated.
p.12
Muscle Contraction Mechanism: Sliding Filament Theory
What is required to cause movement of actin filaments?
Energy must be supplied to myofilaments.
p.38
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What defines pennate muscles?
Fascicles are attached at oblique angles to a central tendon, shorter, and produce greater forces at the sacrifice of speed.
p.29
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is elasticity?
The ability to succumb to an elongating force and then return to normal length when the force is released.
p.12
Muscle Contraction Mechanism: Sliding Filament Theory
How is ATP coupled in muscle contraction?
ATP is coupled to myosin cross-bridges.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is a skeletal muscle?
A complete organ consisting of cells called skeletal muscle fibers.
p.59
Effects of Immobilization on Muscle Structure and Function
What is the potential outcome of muscle hypertrophy in immobilized muscles?
It may be followed by atrophy.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is muscle strength?
The state of being strong, the capacity of a muscle to produce force, and the ability to generate active tension.
p.13
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What happens to the A Bands during muscle contraction?
They do not narrow because the length of myosin does not change.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the sarcolemma?
The plasma membrane of a muscle fiber.
p.28
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
How does increased temperature affect muscle viscosity?
It reduces viscosity and allows the muscle tissue to move with ease.
p.13
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What happens to actin and myosin filaments in a relaxed muscle?
Their lengths are equal in both rested and contracted states.
p.17
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What type of motor neurons innervate fast twitch muscle fibers?
Larger diameter, faster conducting alpha motor neurons.
p.17
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What characterizes motor units in muscles performing delicate and precise movements?
They have a small number of muscle fibers.
p.21
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
Why do small motor units generate less tension?
For energy conservation and the nature of the task.
p.17
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What characterizes motor units in muscles performing powerful but less precise contractions?
They have many muscle fibers.
p.52
Muscle Contraction Mechanism: Sliding Filament Theory
What occurs to the fingers when the wrist extends?
The fingers passively flex due to the tension of the flexor digitorum profundus and superficialis muscles.
p.44
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What happens to the weight a muscle can lift as the speed of contraction increases during concentric contraction?
The muscle is able to work against or lift less weight.
p.1
Functions of Skeletal Muscles
What are the primary functions of skeletal muscles?
To contribute to the body’s needs for mobility and stability.
p.38
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What characterizes fusiform muscles?
Fascicles are parallel and long throughout the muscle, designed for greater shortening distance but less force.
p.47
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
Who is generally stronger, males or females?
Males are generally stronger than females.
p.59
Effects of Immobilization on Muscle Structure and Function
What is a primary structural change in muscles immobilized in a lengthened position?
Increase in the number of sarcomeres, resulting in a decrease in sarcomere length.
p.49
Muscle Contraction Mechanism: Sliding Filament Theory
What happens to the neural activity of antagonist muscles during agonist contraction?
There is a reduction in neural activity.
p.27
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What are the three functions of a synergist muscle?
(1) Provide identical activity to the agonist, (2) prevent undesired joint action, (3) stabilize.
p.26
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is the role of an antagonist muscle?
It provides the opposite anatomic action of the agonist.
p.29
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What does viscoelasticity refer to?
The ability to resist changing its shape when a force is applied, but if the force is sufficient, the tissue cannot return to its original shape.
p.61
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What changes occur in muscle fiber types with aging?
Type II fibers decrease while Type I fibers increase or remain relatively constant.
p.53
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
When does active insufficiency typically occur?
In multi-joint muscles when the muscle is at its shortest length.
p.37
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What are series muscle fibers known for?
They have greater length, are placed end to end, and provide greater speed of motion.
p.54
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What happens to a muscle's ability to produce tension when it is at its shortest?
It is at its lowest, making it difficult for finger flexors to provide a strong grip when the wrist is flexed.
p.38
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How does the number of muscle fibers relate to muscle force?
The more muscle fibers a muscle has, the more force it has the potential to exert.
p.38
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is muscle strength proportional to?
The total cross-sectional area of the muscle.
p.11
Muscle Contraction Mechanism: Sliding Filament Theory
What role does the sarcoplasmic reticulum play during muscle contraction?
It stores and releases calcium ions.
p.12
Muscle Contraction Mechanism: Sliding Filament Theory
What is the primary energy source for muscle contraction?
Adenosine Triphosphate (ATP).
p.61
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is sarcopenia?
The loss of muscle mass as a person ages.
p.32
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
How does strain relate to the elastic properties of tissue?
Strain is directly proportional to the ability of tissue to resist the force.
p.49
Muscle Contraction Mechanism: Sliding Filament Theory
What is the effect of reduced tension on antagonist muscles?
They can subsequently lengthen under less tension.
p.27
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is the role of a fixator/stabilizer muscle?
To surround a joint or body part and contract to stabilize the area, allowing another limb or body segment to exert force and move.
p.37
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What are the characteristics of parallel muscle fibers?
They have greater width and provide greater force.
p.26
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
How do antagonists behave during functional activity?
They are usually inactive but allow passive elongation or shortening for the desired activity.
p.47
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What happens to the number of motor units as individuals age?
The number of motor units declines.
p.8
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What defines the boundaries of a sarcomere?
The portion between two adjacent Z lines.
p.14
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
How does the I Band change in a fully contracted muscle?
The I Band narrows further.
p.55
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is active insufficiency?
The inability of a muscle to generate force when it is shortened over two joints simultaneously.
p.18
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
Why are Type I fibers more fatigue-resistant?
They have more mitochondria and a better-developed blood supply.
p.1
Functions of Skeletal Muscles
How do muscles produce movement?
By controlling the movement of a bony lever around a joint axis.
p.2
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is contractility in muscle properties?
The ability of muscle to shorten forcefully.
p.48
Muscle Contraction Mechanism: Sliding Filament Theory
Which receptors integrate the function of muscle contractions?
Muscle spindle and Golgi tendon organ (GTO).
p.6
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the function of the perimysium?
It surrounds each fascicle.
p.31
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the TOE region in tissue mechanics?
The region where tissue 'takes up the slack' and shows considerable deformation with minimal force.
p.21
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What happens as force increases during muscle recruitment?
Larger motor units are recruited.
p.13
Muscle Contraction Mechanism: Sliding Filament Theory
What happens to the sarcomere during contraction?
It shortens as Z disks move toward each other.
p.47
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
When does muscle strength peak?
Between the ages of 20 and 30 years.
p.7
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the role of tropomyosin in muscle contraction?
It winds along the groove of actin and lies on top of active sites in the resting state.
p.55
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the primary function of the rectus femoris?
To actively flex the hip and extend the knee through their full ranges of motion individually.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What are some factors that influence muscle performance?
Muscle size, architecture of muscle fibers, passive components, physiological length, moment arm length, speed of contraction, active tension, age, and gender.
p.18
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is a key characteristic of Type I fibers regarding blood supply?
They have a better-developed blood supply.
p.35
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is creep in the context of tissue?
The elongation of tissue from the application of a low-level load over time.
p.35
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
In which range do changes occur during creep?
In the plastic range of tissue or structures.
p.55
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is passive insufficiency?
The inability of a muscle to stretch sufficiently when it is lengthened over two joints simultaneously.
p.58
Effects of Immobilization on Muscle Structure and Function
What structural change occurs in the perimysium during immobilization?
There is an increase in the amount of perimysium.
p.39
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How does the number of pennates in a muscle's fiber arrangement affect its force production?
The more pennates a muscle has, the greater force it is able to produce.
p.3
Types of Muscle Tissue: Skeletal, Smooth, Cardiac
What are the characteristics of cardiac muscle?
Involuntary, striated, and uninucleated.
p.2
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What does excitability refer to in muscle tissue?
The capacity of muscle to respond to a stimulus.
p.48
Muscle Contraction Mechanism: Sliding Filament Theory
What happens to elastic energy during the eccentric stretch phase?
It is stored, transitioned, and utilized in the concentric contraction phase.
p.13
Muscle Contraction Mechanism: Sliding Filament Theory
What occurs to actin during muscle contraction?
Actin moves toward each other.
p.52
Muscle Contraction Mechanism: Sliding Filament Theory
What does the passive tension of muscles that cross multiple joints produce?
Passive movements of those joints.
p.31
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the appearance of tissue at resting state in the TOE region?
It has a crimped or wavy appearance.
p.23
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is the effect of concentric activity on body segments?
It produces acceleration of body segments.
p.31
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to tissue when stress is applied in the TOE region?
Some distensibility occurs by straightening and aligning the fibers.
p.23
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What occurs during eccentric contraction?
The muscle lengthens and the points of insertion move away from each other.
p.8
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is a sarcomere?
The basic structural and functional unit of skeletal muscle.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is sarcoplasm?
The cytoplasm of muscles, which contains myofibrils.
p.44
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is the relationship between speed and strength during eccentric contraction?
There is a somewhat proportional relationship; muscle strength increases as speed increases until a certain point.
p.41
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What causes the increase in muscle stiffness?
The muscle’s fascia and tendon.
p.40
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What are the three fascial layers that form the passive elastic component of muscles?
Endomysium, perimysium, and epimysium.
p.10
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What role does Titin play in muscle fibers?
It attaches to Z disks and extends to the M line, functioning as a spring to allow the sarcomere to stretch and recoil.
p.60
Exercise-Induced Muscle Injury
When does Delayed-Onset Muscle Soreness (DOMS) typically begin?
About 24 hours after the activity.
p.7
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What enzyme activity do myosin heads possess?
ATPase, capable of splitting ATP to ADP + PO4.
p.41
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens when passive tension is released?
A greater rebound response or contraction is produced.
p.58
Effects of Immobilization on Muscle Structure and Function
What happens to the ratio of connective tissue to muscle fiber tissue during immobilization?
There is an increase in the ratio of connective tissue to muscle fiber tissue.
p.33
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What does necking indicate about the force required to create tissue damage?
The force or load required is less.
p.22
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is isometric contraction?
A type of contraction where the muscle produces force with no apparent change in the joint angle.
p.11
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the function of the transverse tubular system (T-system) in muscle fibers?
It speeds the transmission of a muscle action potential to all portions of the muscle fiber.
p.1
Functions of Skeletal Muscles
What role do muscles play in joint stability?
They resist extraneous movement of joint surfaces.
p.17
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What type of motor neurons innervate slow twitch muscle fibers?
Smaller diameter, slower conducting alpha motor neurons.
p.29
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is extensibility?
The ability to stretch, elongate, or expand.
p.46
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What are the neural factors that affect muscle tension?
Frequency, number, and size of motor units.
p.47
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How does muscle strength per cross-sectional area compare between males and females?
It is similar in both males and females.
p.59
Effects of Immobilization on Muscle Structure and Function
What type of connective tissue increases in muscles immobilized in a lengthened position?
Endomyseal and perimyseal connective tissue.
p.61
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What happens to skeletal muscle strength as a person ages?
It decreases due to sarcopenia.
p.32
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to collagen bonds in the elastic region?
Some microfailure between the collagen bonds begins.
p.14
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What happens to the ends of actin in a fully contracted muscle?
They overlap at the center of the sarcomere.
p.32
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What occurs when the load is released in the elastic region?
Tissue returns to its original size and shape.
p.23
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is the role of eccentric activity in body movement?
It decelerates body segments and provides shock absorption.
p.55
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What happens when the hip is flexed and the knee is extended simultaneously?
Active insufficiency is reached in the rectus femoris and passive insufficiency in the hamstrings.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How does muscle size affect performance?
Larger muscles generally have a greater capacity to produce force.
p.37
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What does the rule of thumb state regarding longer muscles?
Longer muscles provide that segment’s mobility.
p.58
Effects of Immobilization on Muscle Structure and Function
What happens to sarcomeres when a muscle is immobilized in a shortened position?
There is a decrease in the number of sarcomeres with a compensatory increase in sarcomere length.
p.37
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the role of shorter muscles according to the rule of thumb?
Shorter muscles provide stability.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What role does the speed of muscle contraction play in performance?
It affects the amount of force a muscle can generate.
p.35
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the benefit of a prolonged stretch?
It produces sufficient creep to improve flexibility, especially if applied repetitively.
p.60
Exercise-Induced Muscle Injury
Where does a muscle injury usually occur during a strain?
At the junction between the muscle and tendon.
p.11
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
Where is the sarcoplasmic reticulum (SR) located in relation to the myofibrils?
It runs parallel and superficial to the myofibril, found deep to the sarcolemma.
p.1
Functions of Skeletal Muscles
What is meant by 'approximation of joint surfaces' in muscle function?
It refers to the way muscles help maintain the position of joint surfaces.
p.21
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
In what scenario are smaller motor units recruited first?
During an isometric muscle action.
p.42
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is active tension in muscles?
A muscle develops tension less than its resting length during contraction.
p.23
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What happens during concentric contraction?
The muscle shortens and the proximal and distal insertion points move closer together.
p.46
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What mechanical properties influence muscle tension?
Isometric length-tension relationship and force-velocity relationship.
p.44
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is the relationship between speed of contraction and force during concentric contraction?
They are inversely related.
p.53
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is active insufficiency?
It occurs when a muscle becomes shortened to the point where it cannot generate or maintain active tension.
p.31
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What does the TOE region indicate about tissue behavior?
It indicates that tissue can deform significantly without requiring much force.
p.26
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What types of contractions can an agonist produce?
Concentric, eccentric, or isometric contractions.
p.23
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
In what situations is eccentric contraction particularly important?
When landing from a jump or in walking.
p.60
Exercise-Induced Muscle Injury
During which activities do most muscle injuries occur?
Eccentric and deceleration activities.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What are myofibrils?
Bundles of protein filaments arranged parallel to the long axis of the muscle fiber.
p.15
Muscle Contraction Mechanism: Sliding Filament Theory
What happens when acetylcholine opens Ach-gated channels?
Local depolarization of the sarcolemma occurs.
p.37
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is muscle hypertrophy?
The increase in muscle size.
p.35
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the effect of a short stretch on tight muscles/tissues?
Very difficult to stretch; minimal effects.
p.40
Muscle Contraction Mechanism: Sliding Filament Theory
What function does the series elastic component serve?
It allows the contracting muscle fibers to transfer their forces along the tendon to the bone to produce motion.
p.19
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What are the two types of Type II fibers?
Type IIa (fast-twitch oxidative glycolytic) and Type IIb (fast-twitch glycolytic).
p.16
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
How does the contraction of an entire muscle occur?
Through many motor units firing asynchronously and repeatedly.
p.28
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to muscle viscosity when the temperature decreases?
It increases viscosity, causing muscles to become stiff.
p.42
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is passive tension in muscles?
A muscle gains tension when stretched beyond its normal resting length.
p.49
Muscle Contraction Mechanism: Sliding Filament Theory
What must antagonist muscle groups do when the agonist muscle group contracts?
They must relax and lengthen.
p.27
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is a synergist muscle?
A muscle that contracts at the same time as the agonist to provide identical activity, prevent undesired joint actions, or stabilize.
p.2
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is elasticity in muscle properties?
The ability of muscle to recoil to its original resting length after it has been stretched.
p.52
Muscle Contraction Mechanism: Sliding Filament Theory
What happens to the fingers when the wrist flexes?
The relaxed fingers extend due to the passive tension of the extensor digitorum.
p.10
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the function of the Z disk in muscle fibers?
It serves as an attachment point for actin myofilaments.
p.12
Muscle Contraction Mechanism: Sliding Filament Theory
What are the products of ATP splitting during muscle contraction?
Adenosine diphosphate (ADP) and inorganic phosphate (Pi).
p.27
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
How do fixator muscles contribute to movement?
By stabilizing the area, they enable other limbs or body segments to exert force and move effectively.
p.61
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What happens to the number of motor units as a person ages?
There is a decrease in the number of motor units, with remaining units having more fibers per unit.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the Stress-Strain Curve?
A representation of a structure's ability to withstand applied stresses based on deformation.
p.50
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
Can you give an example of passive insufficiency?
Hamstrings during a straight leg raise (SLR) or tenodesis of the wrist.
p.57
Effects of Immobilization on Muscle Structure and Function
How does the immobilization position affect muscles?
It can be either shortened or lengthened.
p.61
Effects of Immobilization on Muscle Structure and Function
What are the effects of increased connective tissue in muscles?
Decreased range of motion (ROM) and increased muscle stiffness.
p.57
Effects of Immobilization on Muscle Structure and Function
What role do fiber types play in the effects of immobilization?
The percentage of fiber types within the muscle influences the effects.
p.50
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the maximum functional excursion of a muscle?
Usually at a maximum of 70% of its resting length.
p.41
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
How is passive tension similar to stretching a rubber band?
As the stretch increases, more tension is produced.
p.18
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
How do Type I fibers break down ATP?
Slowly, due to a slow form of myosin ATPase.
p.60
Exercise-Induced Muscle Injury
What is the recovery time for muscle soreness?
From 5 to 30 days, depending on the severity.
p.60
Exercise-Induced Muscle Injury
What typically causes a muscle strain?
A single high-force contraction of the muscle while lengthened.
p.29
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the clinical application of increased elasticity?
Increased elasticity leads to increased extensibility and decreased viscosity.
p.51
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
How does normal passive insufficiency affect the hamstrings?
It limits the ability of opposing muscles to contract effectively.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is stress in the context of biomechanics?
The force or load that the body or its parts resists.
p.51
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is abnormal passive insufficiency of the hamstrings?
A condition where the hamstrings are unable to stretch adequately, affecting movement.
p.57
Effects of Immobilization on Muscle Structure and Function
What are the effects of immobilization on muscles?
It affects both muscle structure and function.
p.50
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is passive insufficiency?
It occurs when the opposing muscle becomes stretched to the point where it can no longer lengthen and allow movement.
p.53
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is an example of active insufficiency involving the rectus femoris?
Straight Leg Raise (SLR).
p.47
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What factors can create exceptions in muscle strength variations?
Genetics, biological maturation, conditioning levels, and proper diet and exercise.
p.53
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is optimal sufficiency?
Stabilization by antagonists that allows the multi-joint agonist to perform the desired function.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What occurs in the Elastic region of the Stress-Strain Curve?
The material returns to its original shape after the stress is removed.
p.33
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the plastic region in terms of tissue deformation?
It is the range beyond the elastic limit extending to the point of rupture.
p.58
Effects of Immobilization on Muscle Structure and Function
What is a consequence of muscle immobilization in a shortened position?
Loss of weight and muscle atrophy.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What are fasciculi?
Bundles of fascicles or individual muscle fibers.
p.18
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
How do Type I fibers compare to fast-twitch fibers in terms of contraction speed?
They contract more slowly.
p.10
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
Where is the H zone located?
At the center of each A band.
p.51
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to opposing muscles during passive insufficiency?
Their ability to contract is limited due to the inability of the lengthening muscle to stretch further.
p.10
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is unique about the H zone in terms of myofilaments?
Only myosin myofilaments are present; actin and myosin do not overlap.
p.43
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What role do passive elastic components play in muscle tension?
They provide tension beyond the normal resting length.
p.50
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is functional excursion?
The distance to which the muscle is capable of shortening after it has been elongated as far as the joint(s) over which it passes allows.
p.43
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What does active muscle tissue provide in terms of tension?
Tension at lengths less than resting length.
p.55
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the result of active and passive insufficiency in the rectus femoris and hamstrings?
Inability to reach full range of motion in both the hip and knee joints.
p.35
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is an example of creep observed in daily life?
Height difference in the morning vs in the afternoon.
p.33
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to tissue strained in the plastic region when stress is released?
It has permanent deformation.
p.33
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is necking in the context of tissue properties?
It is the weakening of tissue.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What does strain refer to?
The amount of deformation a structure can tolerate before succumbing to stress.
p.60
Exercise-Induced Muscle Injury
What are the two types of muscle injuries?
Gradual or acute onset injuries.
p.43
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What does the total length-tension relationship curve of muscle illustrate?
The relationship between muscle length and the tension it can produce.
p.9
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What gives myofibrils a banded or striated appearance?
The arrangement of myofilaments.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What are the three regions of the Stress-Strain Curve?
Toe region, Elastic region, Plastic region.
p.8
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What are the two types of proteins that compose sarcomeres?
Structural proteins and contractile proteins.
p.37
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is muscle atrophy?
The decrease in muscle size.
p.40
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the series elastic component in muscles?
The tendon and its fascia.
p.19
Motor Units and Muscle Fiber Types: Slow-Twitch vs Fast-Twitch
What is the myoglobin content in Type II fibers?
They have very little myoglobin.
p.22
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
How is isokinetic contraction applied?
Using an isokinetic device.
p.44
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What occurs when the load increases during concentric contraction?
The velocity decreases to zero, resulting in an isometric contraction.
p.61
Effects of Immobilization on Muscle Structure and Function
What changes occur in connective tissue as a person ages?
There is an increase in the amount of connective tissue within the extracellular matrix of the muscle.
p.10
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What is the M line and its function?
The M line is the middle of the H zone and helps hold the myosin myofilaments in place.
p.44
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What happens when the speed during eccentric contraction reaches a critical point?
The muscle is unable to control the load, leading to uncontrollable lengthening or dropping of the load.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What characterizes the Toe region in the Stress-Strain Curve?
Initial deformation where the material begins to stretch.
p.40
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What is the role of the parallel elastic component in muscles?
It complies with the muscle’s change in length.
p.30
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens in the Plastic region of the Stress-Strain Curve?
The material undergoes permanent deformation and does not return to its original shape.
p.19
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What allows Type II fibers to break down ATP more rapidly?
Their myosin heads have a fast form of myosin ATPase.
p.19
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What types of mitochondria do Type II fibers have?
Fewer and smaller mitochondria.
p.57
Effects of Immobilization on Muscle Structure and Function
What factors influence the effects of immobilization?
Immobilization position, percentage of fiber types, and length of the immobilization period.
p.7
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What do myosin heads resemble?
The distal end of a hockey stick.
p.18
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What role does myoglobin play in Type I muscle fibers?
It binds oxygen and acts as an oxygen reservoir.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How does the moment arm length influence muscle performance?
A longer moment arm can increase the torque produced by the muscle.
p.57
Effects of Immobilization on Muscle Structure and Function
How does the length of the immobilization period affect muscles?
Longer periods can lead to more significant changes in structure and function.
p.60
Exercise-Induced Muscle Injury
How long can DOMS last after exercise?
It may continue for up to 10 days post-exercise.
p.22
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
When does isokinetic contraction rarely occur?
During normal human movements.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
What is the length-tension relationship in muscles?
It refers to the physiological length of the muscle that affects its ability to generate force.
p.5
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What proteins compose thick and thin myofilaments?
Thick myofilaments are composed of myosin, and thin myofilaments are composed of actin.
p.8
Muscle Fiber Structure: Sarcomeres, Myofibrils, and Myofilaments
What are examples of structural proteins in sarcomeres?
Z line, M line, and Titin.
p.36
Muscle Performance Factors: Size, Architecture, and Length-Tension Relationship
How do age and gender influence muscle performance?
They can affect muscle size, strength, and overall performance capabilities.
p.60
Exercise-Induced Muscle Injury
What happens if eccentric exercise is repeated after recovery?
Muscle soreness does not occur, and the muscle adapts.
p.22
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What characterizes isotonic contraction?
Shortening of the muscle occurs while the load on the muscle remains constant.
p.40
Muscle Properties: Contractility, Excitability, Extensibility, Elasticity
What happens to the fascia when slack is removed?
It becomes passively stretched as the muscle continues to lengthen.
p.58
Effects of Immobilization on Muscle Structure and Function
What change occurs in collagen fibril orientation during muscle immobilization?
Collagen fibril orientation becomes more circumferential.
p.15
Muscle Contraction Mechanism: Sliding Filament Theory
What causes muscle relaxation after contraction?
Removal of calcium from myofibrils.
p.22
Muscle Contraction Types: Isometric, Isotonic, Eccentric, Concentric
What is isokinetic contraction?
A contraction that occurs when the rate of movement is constant.
