Download NASMChapter02

Chapter 2
Basic Exercise Science
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Purpose
• To provide the fitness professional with the
fundamental concepts that pertain to the definition,
structure, and function of the human movement
system (kinetic chain).
• By understanding basic anatomic structures and
physiologic functions, the fitness professional will
gain comprehensive insight into how the human body
operates.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Objectives
• After this presentation, the participant will be able to
explain the basic structure and function of:
• The nervous system
• The skeletal system
• The muscular system
• The endocrine system
• The participant will also be able to describe how
these systems respond and adapt to exercise.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Introduction
Human Movement System:
• Movement is accomplished through the functional
integration of three systems: the nervous, skeletal,
and muscular systems.
• These systems work in concert to produce motion
(kinetic) or human movement.
• All components must work together to produce sound
movement; if one component is not working well, it
will affect the others and cause kinetic chain
impairments.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Kinetic Chain
The kinetic chain
• Kinetic means force(s); chain refers to a system
that is linked together or connected.
• All components work together to manipulate
human motion.
• If one component of the kinetic chain is not
working properly, it will affect the others and
ultimately affect the movement.
Kinetic Chain
Nervous System
Muscular System
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Skeletal System
The Nervous System
• The nervous system is one of the main organ
systems of the body and contains specialized cells
that transmit and coordinate signals, providing a
communication network within the body.
• The nervous system comprises two main
components:
• The central nervous system (CNS) is
composed of the brain and spinal cord.
• The peripheral nervous system (PNS) is the
nerves that communicate with the CNS.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Nervous System
• The nervous system is a
communication network within
the human body that allows us to
gather information about our
internal and external
environments, process and
interpret the information, and
respond.
• Its three primary functions are:
•
Sensory
•
Integrative
•
Motor
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Nervous System
• Sensory: The ability of the nervous system to sense
changes in either the internal or external
environment.
• Integrative: The ability of the nervous system to
analyze and interpret the sensory information to allow
for proper decision making, producing the appropriate
response.
• Motor: The neuromuscular response to the sensory
information.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Proprioception
• The body’s ability to sense the relative position of
adjacent parts of the body.
• Training the body’s proprioceptive abilities will
improve balance, coordination, and posture and
enable the body to adapt to its surroundings without
consciously thinking about movement.
• Thus, it becomes important to train the nervous
system efficiently to ensure proper movement
patterns, which enhances performance and
decreases the risk of injury.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Nervous System
• Movement is a response to our sensory information
and is, therefore, dictated by the nervous system.
• This reflects the importance of training in a
multisensory environment.
• The most effective way to create positive long-term
results in a client is to directly affect (properly train)
his or her nervous system.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Neuron
• The functional unit of the
nervous system is known as the
neuron.
• Neurons are composed of three
main parts:
•
Cell body: Cell organelles
(nucleus, mitochondria,
lysosomes, and Golgi
complex)
•
Axon: Provides
communication from the
brain or spinal cord to other
parts of the body
•
Dendrites: Responsible for
gathering information from
other structures of the body
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Neuron
There are three main functional classifications of
neurons determined by the direction of their nerve
impulses:
• Sensory: Transmits afferent nerve impulses from
receptors to the brain or spinal cord
• Motor: Transmits efferent nerve impulses from the
brain or spinal cord to the effector sites, such as
muscles or organs
• Interneuron: Transmits nerve impulses from one
neuron to another
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Central Nervous System
The CNS consists of the brain and the spinal cord.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Peripheral Nervous System
• Contains 12 cranial nerves and 31 pairs of spinal nerves (that
branch out from the brain and spinal cord, respectively) as well as
all sensory receptors.
• Function:
•
•
Provide a connection for the nervous system to activate different bodily
organs such as muscles (motor information).
Relay information from the bodily organs back to the brain, providing a
constant update of the relation between the body and the environment
(sensory information).
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Peripheral Nervous System
Two further subdivisions of the PNS include the somatic
and autonomic nervous systems:
• The somatic nervous system consists of nerves that
serve the outer areas of the body and skeletal muscle
and are largely responsible for the voluntary control
of movement.
• The autonomic nervous system supplies neural input
to the involuntary systems of the body.
• The autonomic system is further divided into the
sympathetic and parasympathetic nervous systems.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Sensory Receptors
• Specialized structures located throughout the body, designed
to transform environmental stimuli (heat, light, sound, taste,
and motion) into sensory information that the brain or spinal
cord can interpret to produce a response:
•
Mechanoreceptors respond to mechanical forces (touch
and pressure).
•
Nociceptors respond to pain (pain receptors).
•
Chemoreceptors respond to chemical interaction (smell
and taste).
•
Photoreceptors respond to light (vision).
• For relevance to this course, we will focus attention on the
mechanoreceptors.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Mechanoreceptors
• Muscle spindle: Sensitive to change in length and
rate of length change in muscle.
• Golgi tendon organ: Sensitive to changes in
muscular tension and rate of tension change.
• Joint receptors: Respond to pressure, acceleration,
and deceleration of the joint.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Physical Activity and the Nervous
System
• Early stage improvements to physical activity are
largely due to changes in the way the CNS and PNS
coordinate movement.
• Unsuccessful activity can be modified with sensory
input to improve performance.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Skeletal System
• Framework for our
structure and
movement.
• Resting ground for the
muscles of our body.
• Bones form junctions
that are connected by
muscles and connective
tissue known as joints.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Divisions of the Skeletal System
• Axial skeleton:
• Skull
• Rib cage
• Vertebral column
• Appendicular skeleton:
• Upper and lower extremities
• Shoulder and pelvic girdles
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Bone Growth
Bones under go remodeling throughout life cycle:
• Osteoclasts break down old bone tissue.
• Osteoblasts build up new bone tissue.
• Remodeling is the constant process of these cells.
• In children, osteoblasts are more active; as we age,
osteoclasts become more active.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Bones
Long bones:
• Long cylindrical shaft and
irregular or widened ends
• Epiphysis: End of long
bone
• Diaphysis: Shaft of long
bone; main production of red
blood cells (RBCs)
• Epiphyseal plate: Where
bone growth (length) occurs
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of bones
Long bones:
• Periosteum: Tough
membrane that coats bone
• Medullary cavity: Central
cavity of bone where marrow
is stored
• Articular cartilage:
Cartilage that covers the
articular surfaces of bones
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Bones
Short bones:
• Similar in length and width
and appear somewhat
cubical in shape
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Bones
Flat bones:
• Thin, protective
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Bones
Irregular bones:
• Unique shape and function
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Bone Markings
Depressions:
• Flattened or indented
portions of the bone
• Common depressions:
•
•
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Fossa
Sulcus
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Bone Markings
Processes:
• Projections protruding from the bone to which muscles,
tendons, and ligaments attach
• Common processes:
•
Condyle
•
Epicondyle
•
Tubercle
•
Trochanter
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Vertebral Column
Vertebral column:
• Series of irregularly shaped bones
called vertebrae.
• Houses the spinal cord.
•
Cervical spine has 7 (concave curve)
•
•
•
•
vertebrae.
Thoracic spine has 12 (convex curve).
Lumbar spine has 5 (concave curve).
Sacrum is fused triangle attached to
pelvis.
Coccyx is tail bone.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Joints
• One bone that articulates with another bone.
• Joint motion is referred to as arthrokinematics.
• Typical joint motions seen in the human articular
system include:
• Roll: Rolling on joint surface on another such as femoral
•
•
condyles rolling over the tibial condyles during a squat
Slide: Sliding of a joint surface across another such as
tibial condyles moving (sliding) across the femoral
condyles during a knee extension
Spin: Rotation of one joint surface on another such as
head of the radius rotating on the end of the humerus
during pronation and supination of the forearm
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Classifications of Joints
• Synovial joints:
• Produce synovial fluid
• Have a joint cavity and fibrous connective tissue
• Example: Knee
• Nonsynovial joints:
• No joint cavity and fibrous connective tissue
• Little or no movement
• Example: Sutures of the skull
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Functions of Joints
• Provide the bones a means to be manipulated,
allowing for movement throughout segments of the
body.
• Provide stability, allowing for movement to take place
without unwanted movement.
• All joints in the human body are linked together;
movement of one joint will directly affect the motion of
others.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Joint Connective Tissue
• Ligaments connect bone to
bone and provide static and
dynamic stability as well as
proprioception.
• Characterized by poor
vascularity and do not repair
or adapt as easily as other
tissues in the body.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Weight-bearing Exercise
Weight bearing exercise:
• Exercise that forces the body to work against gravity:
• Running, lifting weights, calisthenics are
weight bearing
• Swimming and cycling are not
• Helps build and maintain bones, muscles, and
connective tissues; burns lots of calories.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Muscular System
• Muscles generate
internal tension that,
under the control of the
nervous system,
manipulates the bones
of our body to produce
movement.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Structure of Skeletal Muscle
Muscle is the compilation of many individual muscle fibers neatly wrapped together
with connective tissue to form bundles:
• The first bundle is the actual muscle itself, wrapped by an outer layer of
connective tissue called fascia; the inner layer immediately surrounding the
muscle is called epimysium.
• The next bundle of muscle fiber is a fascicle that is wrapped by connective tissue
called perimysium.
• Each fascicle is made up of many individual muscle fibers that are wrapped by
connective tissue called endomysium.
• Each layer of connective tissue extends the length of the muscle, helping to form
the tendon.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Connective Tissue
• Tendons are the structures
that attach muscles to bone
and provide the anchor from
which the muscle can exert
force and control the bone
and joint.
• They have poor vascularity
(blood supply), which leaves
them susceptible to slower
repair and adaptation.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Muscle Fibers
• Contain typical cell
components:
•
Cellular plasma called
sarcoplasm (contains
glycogen, fats, minerals,
and oxygen-binding
myoglobin)
•
Nuclei
•
Mitochondria (transform
energy from food into
energy for the cell)
• Unlike typical cells, they also
have structures called
myofibrils.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Contractile Elements
• Myofibrils contain myofilaments
that are the actual contractile
components of muscle tissue:
•
•
Actin
Myosin
• Actin (thin) and myosin (thick)
filaments form sections known as a
sarcomere.
• A sarcomere is the functional unit
of the muscle, much like the neuron
is for the nervous system:
• It lies in the space between two Z
lines; each Z line denotes another
sarcomere along the myofibril.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Contractile Elements
• Two protein structures that are
also important to muscle
contraction are tropomyosin
and troponin.
• Tropomyosin is located on the
actin filament and blocks
myosin binding sites located on
the actin filament, keeping
myosin from attaching to actin
while the muscle is in a relaxed
state.
• Troponin, also located on the
actin filament, plays a role in
muscle contraction by providing
binding sites for both calcium
and tropomyosin when a
muscle needs to contract.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Troponin
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Generating Force in a Muscle
Neural activation:
• Essential for a muscle to
manipulate force for either
movement or stabilization.
• Generated by the
communication between the
nervous system and the
muscular system or the motor
unit (motor neuron and the
muscle fibers with which it
connects).
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Neural Activation
1.
2.
3.
4.
5.
6.
Electrical impulses are transported from the CNS down the axon of the neuron.
When the impulse reaches the end of the axon (axon terminal), chemicals called
neurotransmitters are released.
Neurotransmitters (chemical messengers) cross the synapse between the neuron and muscle
fiber, transporting the electrical impulse from the nerve to the muscle. The specific
neurotransmitter used for muscle contraction is acetylcholine (ACh).
ACh falls into receptor sites on the muscle fiber, specifically designed for its attachment.
Once attached, ACh stimulates the muscle fibers to go through a series of steps that produce
muscle contractions.
Summation causes either all motor fibers of a unit to fire or none; this is the “all or nothing law.”
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Sliding Filament Theory
The proposed process of how the contraction of the
filaments within the sarcomere takes place:
• A sarcomere shortens as a result of the Z lines moving closer
together.
• The Z lines converge as the result of myosin heads attaching to the
actin filament and asynchronously pulling (power strokes) the actin
filament across the myosin.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Excitation–Contraction Coupling
•
•
•
•
•
•
A nerve impulse (action potential) is transmitted through the neuron and
down the axon to where the axon meets the muscle fiber (neuromuscular
junction) and releases ACh.
ACh transports across the synapse and binds to its receptor on the
muscle fiber.
This continues the neural message (action potential) to the muscle fiber
that triggers the release of calcium (Ca2+) into the sarcoplasm (where the
actin and myosin are located).
Ca2+ binds to the protein troponin, forcing the protein tropomyosin to
move away from the myosin binding site and allowing for myosin to
attach to actin.
Myosin attaches to actin, creating a pull of the filaments across each
other (sliding filament theory) and causing the muscle to shorten
(contract).
Once the neural impulse for contraction subsides, calcium concentration
in the sarcoplasm decreases, forcing myosin to unbind with the actin,
ending the muscle contraction.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Muscle Fiber Types
• Type I: Slow Twitch
•
•
•
•
•
•
Higher in capillaries, mitochondria, and myoglobin
Increased oxygen delivery
Smaller in size
Produce less force
Slow to fatigue
Long-term contractions (stabilization)
• Type II: Fast Twitch
•
•
•
•
•
•
Lower in capillaries, mitochondria, and myoglobin
Decreased oxygen delivery
Larger in size
Produce more force
Quick to fatigue
Short-term contractions (force and power)
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Muscle Fiber Arrangement
Muscle Types and Fiber Arrangements
Type
Fiber Arrangement
Example
Fusiform
Parallel to direction of tendon
Biceps brachii
Fan-shaped
Diverges from broad
attachment to narrow one
Pectoralis major
Longitudinal
Parallel to line of pull
Sartorius
Quadrilateral
Parallel to line of pull
Rhomboid
Unipenniform
Oblique to line of pull
Posterior tibialis
Bipenniform
Oblique to line of pull
Rectus femoris
Multipenniform
Oblique to line of pull
Deltoid
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Muscles As Movers
• Agonist muscles act as prime movers: Gluteus
maximus is an agonist for hip extension.
• Synergist muscles assist prime movers during
movement: Hamstring and the erector spinae are
synergistic with the gluteus maximus during hip
extension
• Stabilizer muscles support or stabilize the body while
the prime movers and the synergists perform the
movement patterns: Transversus abdominis, internal
oblique, and multifidus stabilize the low back, pelvis,
and hips during hip extension.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Endocrine System
System of glands that secrete hormones that control
bodily function:
• Consists of host organs, chemical messengers,
target cells.
• Target cells bind specifically to hormones.
• Regulates body functions (growth, metabolism, and
response to stress).
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Endocrine Glands
Primary glands of the endocrine
system include:
• Pituitary “master” gland with
anterior, posterior and
intermediate globes
• Hypothalamus
• Thyroid gland
• Adrenal gland
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Endocrine Glands
Pituitary gland:
• Master control gland has three lobes:
•
•
•
Anterior: Secretes growth hormone, prolactin,
adrenocorticotropic hormone (adrenal glands)
thyroid-stimulating hormone (thyroid), folliclestimulating hormone (sex organs) and luteinizing
hormone (sex organs).
Intermediate: Secretes melanocyte-stimulatinh
hormone (skin).
Posterior: Secretes vasopressin (fluid retention) and
oxytocin (childbirth).
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Endocrine Glands
• Thyroid gland: Regulates metabolism.
• Adrenal glands: “Fight-or-flight” hormones and
inflammation (epinephrine “adrenaline” and
norepinephrine).
• Testosterone is produced in testes and adrenal
glands; men produce 10 times more than women.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Blood Glucose Control
• Control of blood glucose levels regulated by the
pancreas to prevent wide swings in blood glucose
levels.
• Insulin: Brings glucose into cells from blood stream,
resulting in net drop in blood sugar levels.
• Glucagon: Signals the liver and muscles to break
down and release glycogen stores; results in net rise
of blood sugar levels.
• Exercise improves body’s utilization of glucose.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Effects of Exercise
• Epinephrine is released during exercise, which
increases heart rate, elevates blood glucose, and
opens airways.
• Exercise is response to “flight-or-fight” mechanism.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Hormones
• Both produced by men and women
– Testosterone-men produce 10 times more is
produced in testes and adrenal glands, major
anabolic agent
– Estrogen-produced in ovaries and adrenal glands,
women produce significantly more
– Cortisol produced in adrenal is main catabolic agent
– Growth Hormone-produced in pituitary major
anabolic agent
– Thyroid-Found in in neck, controls metabolism
– Exercise can elevate all these hormones
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins
Summary
• The three components of the kinetic chain (nervous, muscular,
and skeletal systems) all work together to produce movement.
• The nervous system is composed of billions of neurons that
transfer information throughout the body, through two
interdependent systems: the CNS and the PNS.
• The skeletal system is the body’s framework and is made up of
bones and joints in two divisions: axial and appendicular.
• The muscular system is made up of many individual fibers
attached to bones by way of the tendons. Muscles generate
force through neural activation, the sliding filament theory, and
excitation–contraction coupling.
Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins