Chapter 2 Basic Exercise Science

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Chapter 2 Basic Exercise Science
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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
• Describe how these systems respond and adapt to
  exercise

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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 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.

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Kinetic Chain

• The Kinetic Chain
• Kinetic means force or motion.
• 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.

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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 is comprised of 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

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The Nervous System

• The nervous system is a communication network
  within the human body.
• It allows us to gather information about our
  internal and external environments, process and
  interpret the information, and respond.
• Three primary functions
• Sensory
• Integrative
• Motor

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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.

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Proprioception

• Is the bodys ability to sense the relative
  position of adjacent parts of the body. On the
  test they will define proprioception as the
  cumulative neural input from all sensory
  afferents to the Central Nervous System. Training
  the bodys proprioceptive abilities will improve
  balance, coordination, and posture, and enable
  the body to adapt to its surroundings without
  consciously thinking about movement.
• It is important to train the nervous system
  efficiently to ensure proper movement patterns
  which can enhance performance and decrease the
  risk of injury.

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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 using different balance
  tools, ex. Bosu ball, Balance pad, Dyna Disc
• The most effective way to create positive
  long-term results in a client is to directly
  affect (properly train) his or her nervous system.

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The Neuron

• The functional unit of the nervous system is
  known as the neuron.
• Neurons are composed of three main parts
• Cell body
• Includes cell structures like (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

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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

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Central Nervous System

• Consists of the brain and the spinal cord

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Peripheral Nervous System

• Contains 12 cranial nerves and 31 pairs of spinal
  nerves, that branch out from the brain and spinal
  cord, 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).

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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 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 dived into the
  sympathetic and parasympathetic nervous systems.
  The sympathetic nervous system initiates the
  Fight or Flight response while the
  parasympathetic initiates the Rest and Digest.

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Sensory Receptors

• Specialized structures located throughout the
  body are designed to transform environmental
  stimuli (heat, light, sound, taste, 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.

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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.

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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

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Divisions of the Skeletal System

• Axial Skeleton
• Skull
• Rib cage
• Vertebral column
• Appendicular Skeleton
• Upper and lower extremities
• Shoulder and pelvic girdles

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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
• As children Osteoblasts are more active, as we
  age Osteoclasts become more active

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Types of Bones

• Long
• Long cylindrical shaft and irregular or widened
  ends
• Epiphysis ends of long bones
• Diaphysis shaft of long bones main production of
  red blood cells (RBCs)
• Epiphyseal plate is where bone growth (length)
  occurs

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Types of Bones

• Short
• Similar in length and width and appear somewhat
  cubical in shape

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Types of Bones

• Flat
• Thin, protective

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Types of Bones

• Irregular
• Unique shape and function

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Vertebral Column

• Vertebral column A series of irregularly shaped
  bones called vertebrae that houses the spinal
  cord.
• Cervical has 7 (concave curve)
• Thoracic has 12 (convex curve)
• Lumbar has 5 (concave curve)
• Sacrum is fused triangle attached to pelvis
• Coccyx is tail bone

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Joints

• One bone that articulates with another bone
• Joint motion is referred to as arthrokinematics
• Typical joint motions seen in the human articular
  system
• Roll Rolling on joint surface on another
• Femoral condyles rolling over the tibial condyles
  during a squat
• Slide Sliding of a joint surface across another
• Tibial condyles moving (sliding) across the
  femoral condyles during a knee extension
• Spin Rotation of one joint surface on another
• Head of the radius rotating on the end of the
  humerus during pronation and supination of the
  forearm

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Function 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

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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

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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
• Help build and maintain bones, muscles, and
  connective tissues, burns lots of calories

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The Muscular System

• Muscles generate internal tension that, under the
  control of the nervous system, manipulates the
  bones of our body to produce movement.
• The Muscular System also is needed to stabilize
  and complete the cycle of movement production.

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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 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.

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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.

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Muscle Fibers (Cells)

• 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.

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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

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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.

Troponin
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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 unit motor neuron and the muscle fibers
  with which it connects.

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Neural Activation

1. Electrical impulses are transported from the
   central nervous system down the axon of the
   neuron.
2. When the impulse reaches the end of the axon
   (axon terminal), chemicals called
   neurotransmitters are released.
3. 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 that initiates muscular
   contraction is acetylcholine (ACh).
4. ACh falls into receptor sites on the muscle
   fiber, specifically designed for its attachment.
5. Once attached, ACh stimulates the muscle fibers
   to go through a series of steps that produce
   muscle contractions.
6. Either a summation causes all motor fibers of a
   unit to fire or none, this is the all or nothing
   law

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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.

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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)

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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

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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,
  response to stress)

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Endocrine Glands

• Primary glands of the endocrine system include
• Pituitary master gland with anterior, posterior
  and intermediate globes, hypthalamus, thyroid and
  adrenal glands

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Endocrine Glands

• Pituitary- Master control gland has three lobes
• Anterior- Secretes growth hormone, prolactin,
  ACTH (adrenal glands) TSH (Thyroid), FSH (sex
  organs) and LH (sex organs).
• Intermediate lobe secretes MSH (skin)
• Posterior lobe secretes ADH (fluid retention),
  oxytocin (childbirth),

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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

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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, results in net drop in blood sugar levels
• Glucagon- Signals the liver and muscles to
  breakdown glycogen stores and release, results in
  net rise on blood sugar levels
• Exercise improves bodies utilization of glucose

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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

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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
  central nervous system and the peripheral nervous
  system.
• The skeletal system is the bodys 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,
  sliding filament theory, and excitationcontractio
  n coupling.