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Muscular Strength and Endurance


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Title: Muscular Strength and Endurance

Muscular Strength and Endurance
  • Chapter 4

Types of Muscle Tissue
  • Skeletal Muscle predominant muscle tissue,
    which is attached to the skeleton of the body.
    It is under voluntary control. It attaches
    across the joints and will contract and generate
    force when stimulated. Movement is a result of
    the contraction of this muscle tissue.
  • Smooth Muscle typically found in hollow organs
    of the body, such as blood vessels, stomach and
    intestines. It is under involuntary control.
  • Cardiac Muscle found only in the heart. It is
    under involuntary control.

Muscular Strength and Endurance
  • Muscular Strength The maximal force that a
    muscle can generate for a single maximum effort.
    It is usually assessed by measuring strength
    using a one-repetition maximum (1-RM) procedure
    with either free weights or some form of variable
    resistance weight machine.
  • Muscular Endurance The ability of the muscle to
    exert a submaximal force repeatedly or
    continuously over time. Usually measured by
    determining the maximum number of repetitions
    that can be performed. (push-ups/curl-ups)

Basic Skeletal Muscle Characteristics
  • Musculo-tendinious unit consists of muscle
    belly and tendons. When a muscle contracts
    (shortens), it moves a bone by pulling on the
    tendon that attaches the muscle to the bone.
  • Muscles consist of individual muscle cells or
    muscle fibers. They are connected in bundles. A
    single muscle is made up of many bundles of
    muscle fibers covered by layers of connective
    tissue that hold the fibers together.
  • The muscle fibers are made up of smaller units
    called myofibrils. When the brain signals the
    muscle to contract, protein filaments within the
    myofibrils slide across one another causing the
    muscle fiber to shorten. (actin and myosin -
    Sliding Filament Theory)

Muscle Unit
Types of Muscle Fibers
  • Muscle fibers vary in their structural and
    functional characteristics. Color of muscle
    fiber is one difference.

Types of Fibers
  • Slow Twitch (Red) Type I High capacity for
    aerobic energy supply. Very efficient in
    producing ATP. Fatigue resistant. Speed of
    contraction of slow twitch fibers is much slower
    than fast-twitch. They are adapted for low
    intensity, long duration activities. They
    utilize aerobic energy system for fuel.
  • Fast Twitch (White) Type II High capacity for
    rapid force development. Rely on anaerobic
    metabolism for fuel. They are explosive and
    powerful, but fatigue quickly.

  • Weight training causes the SIZE of the individual
    muscle fibers to increase by increasing the
    number of myofibrils.
  • HYPERTROPHY the development of large muscle
  • Most muscles contain a mixture of slow and fast
    twitch fibers.
  • Inactivity reverses the process
  • called ATROPHY.

Motor Units
  • To exert force, the body will recruit one or
    more motor units (nerves connected to fibers) to
    contract. There can be anywhere from 2 to 100s
    of fibers in each unit. The number of motor
    units recruited depends on the amount of strength
  • Small weight ? Few motor units
  • Large weight ? More motor units
  • Strength training improves the bodys ability to
  • motor units. (Muscle Learning), thus increasing
  • strength even before muscle size increases.

Motor Units
  • Motor units (nerves connected to muscle fibers)
    are recruited to exert force

Motor Unit Recruitment
  • Increased muscular strength, endurance
  • Increased muscle size (hypertrophy)
  • Increased flexibility or range of motion
  • Decreased body fat
  • Increased lean body mass
  • Increased metabolism
  • Improved physical appearance
  • Increased performance in activities
  • Assists in prevention of osteoporosis
  • Moderate decreases in blood pressure
  • Improved blood lipid profiles

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Assessing Muscular Strength and Endurance
  • Muscular strength assessed by determining
    repetition maximum (1 RM), the maximum resistance
    that can be lifted once
  • Muscular endurance assessed by counting the
    maximum number of repetitions of a muscular

Training Principles
  • Overload A gradual increase in the frequency,
    duration, or intensity of the activity must occur
    is any physiological adaptation is going to
    occur. For resistive training, this principle
    specifically suggests that for greater gains in
    strength, endurance or power to occur there must
    be a manipulation of these factors.
  • For endurance, increase the number of repetitions
    in a set, reduce the recovery time between sets
    or a combination of the two.
  • For strength, increase the resistance or load,
    while restricting the number of repetitions in a
    set to 10 or lower.
  • In each case, over time the muscle will adapt to
    the changes and alter its structure and/or
    function, leading to greater gains.

Training Principles
  • Specificity The human body adapts to how it is
    being trained. The systems of the body will
    physiologically adapt, specifically to the type
    and nature of exercise training. How the body
    adapts, and how much it improves, is directly
    related to how hard, and in what manner, it is
  • Example If you want a stronger upper body, you
    must train the chest, back, shoulders, and arms.
  • If you want bigger quadriceps, you must train
  • If you want to increase muscular strength, you
    need to follow the guidelines for strength
    development more weight, less reps. For
    endurance, less weight, more reps.

Training Principles
  • Reversibility Periods of interrupted training
    will cause, in time, a reduction in
    strength/endurance. Muscle tissue will not
    retain, for any length of time, any gains in
    strength or endurance associated with resistive
    training if training is discontinued or
    drastically reduced.
  • Atrophy A reduction of muscle size. This is a
    result of reduced cross sectional area of
    individual muscle cells (size), from lack of
    training or a decrease in the number of cells,
    which is more associated with aging.
  • Rate of atrophy due to detraining is
    approximately 1 per week, dependent on the
    nature and extent of detraining. For example,
    total bed rest could be more damaging than just
    quitting your resistive training program.

Types of Muscular Contractions
  • Isometric (Static) Contractions that generate
    muscle tension, but no change in the length of
    the muscle or movement of a joint.
  • Example tighten the abdominal muscles while
    sitting still.
  • Isometric exercises develop strength only at or
    near the joint angle where they are performed,
    not through the entire joint ROM.
  • Used to strengthen muscles after injury or
    surgery when movement of a joint could delay
  • For maximum gains hold the isometric contraction
    for 6 seconds and repeat 5-10 times.

Types of Muscular Contractions
  • Isotonic (Dynamic) Involves applying force with
    movement. Muscle contractions occur while
    muscles change length.
  • Most popular type of exercises for increasing
  • Can be performed with free weights, machines, or
    your own body weight.
  • Concentric Contractions that occur when a
    muscle shortens a positive contraction.
  • Eccentric Contractions that occur when a muscle
    lengthens a negative contraction.

Factors Affecting MSE Training
  • Muscle size
  • Strength training does not increase the strength
    of contraction of the muscle cells, but rather
    increases in strength result from a proportional
    increase in the diameter or size of the muscle
  • Gender
  • Women will not experience as much hypertrophy as
    men will. This is due to lower levels of
  • Age
  • Loss of skeletal muscle tissue is associated with
    aging, however the greatest losses are related
    more to physical inactivity and sedentary
    lifestyle and may be preventable and/or

  • Frequency Training with weights should be 2-3
    nonconsecutive days/week. Muscles require a
    24-48 hour rest between workouts.
  • Intensity The amount of weight (resistance)
    lifted. This determines how your body will adapt
    to weight training and how quickly changes will
  • For strength, may use 80 of 1RM for 1-8
  • Higher amount of weight ? Less Repetitions
  • For endurance, use 40-60 of 1RM for 15-20
  • Lower amount of weight ? More Repetitions
  • For general fitness, use 70 of 1 RM for
    10-12 repetitions.

Training for Strength versus Training for
FITT Principle for Strength Training
  • Time of Exercise (Repetitions and Sets)- to
    improve fitness, you must do enough repetitions
    of each exercise to FATIGUE your muscles. The
    number of repetitions needed to cause fatigue
    depends on the amount of weight lifted.
  • For a general fitness program for both strength
    and endurance, complete 8-12 repetitions of 8-10
    different exercises, balancing the muscle groups.
    (Ab and calf exercises may require more
  • Set Refers to the number of repetitions of an
    exercise. Start with 1-2 sets, and build up to
    increase strength. Allow enough rest time
    between sets for the muscles to work at a high
    enough intensity. Can work a different muscle
    group during the rest period to save time.

  • Type or Mode of Exercise For overall fitness
    include exercises for your neck, upper back,
    shoulders, arms, chest, abdomen, lower back,
    thighs, buttocks, and calves about 8-10
    exercises in all.
  • Balance between agonist (the muscle contracting)
    and antagonist (the opposing muscle which must
    relax and stretch) muscle groups.
  • Example If you do leg extensions (quadriceps),
    also do leg curls (hamstrings).
  • Work the large muscle groups or multiple joints
    before working small muscle groups. Example A
    chest press (chest, arms) should be performed
    before a lateral raise (deltoids).
  • See back of chapter for exercises.

Systems of Training
  • SET SYSTEM Most popular type of training.
    Person does an exercise for a given number of
    repetitions, or a set, then rests before
    performing another set.
  • SUPERSETS An exercise set for a particular
    muscle group is followed by an exercise for the
    opposing muscle group. (biceps/triceps)
  • SUPER MULTIPLE SET Same concept as supersets,
    but the lifter completes all of the sets for a
    given muscle group, then completes the same
    number of sets for the opposing muscle group.
  • SPLIT ROUTINE Requires a great amount of time
    and work. Lifter alternates muscle groups worked
    each day, and works out more days/week.
  • Example M, W, F work arms, legs and abs T,
    Th, Sa, work chest, shoulders and back.

Systems of Training
  • PYRAMID SYSTEM Adding weight until the lifter
    can complete only one repetition.
  • Example Bench press with a set of 10 reps, then
    add weight, complete 8-9 reps, add weight,
    complete 6-7 reps continuing until the final set
    is 1 repetition. (Light to Heavy) Can also
    pyramid down from heavy to light weights,
    increasing the repetitions as weight is removed.
  • NEGATIVES Emphasis is placed on the eccentric
    part of the exercise. Slower repetitions are
    suggested. (Muscle soreness is usually a
  • SUPER SLOW Both concentric and eccentric
    movements are slowed down to achieve maximum

Making Progress
  • To start Choose a weight with which you can do
    812 repetitions with good form
  • To progress, use the two-for-two rule If your
    goal is 8-12 repetitions, add resistance when you
    do more than 14 repetitions at your previous two
  • Maintain good form at all times
  • Track your progress

Safety Considerations
  • 1. WARM up prior to the workout.
  • 2. Breathe properly. Breathe out with strenuous
    position, and in with less strenuous position.
  • 3. Use spotters with free weights in any
    exercise where you could lose control of the
  • 4. Always use lock-collars on bar ends so plates
    dont fall off.
  • 5. Use proper lifting techniques

Machines vs Free Weights
  • Machines
  • Safe
  • Convenient
  • Easy to Use
  • Dont need spotter
  • Rapid, effortless change of resistance
  • Controlled range of motion
  • Provide both positive and negative
  • Expensive
  • Require a lot of space
  • Free Weights
  • Requires more balance, coordination
  • Allow for a free range of motion
  • Versatile
  • Provide positive and negative resistance
  • Require a number of muscle groups to work
    together when lifting
  • May require a spotter
  • Require time and effort to adjust resistance.

Muscular System
Muscular System
A Caution About Supplements and Drugs
A Caution About Supplements and Drugs
  • Supplements taken to increase muscle growth
  • Anabolic steroids
  • Human chorionic gonadotrophin (HCG)
  • Growth hormone
  • Dehydroepiandrosterone (DHEA) and androstenedione
  • Insulin and insulin-like growth factor (IGF-1)
  • Beta-agonists
  • Protein, amino acid, and polypeptide supplements
    and so-called metabolic optimizing meals

Side Effects of Anabolic Steroids
  • Liver damage and tumors
  • Reduced HDL
  • High blood pressure, heart disease, cancer
  • Depressed immune function
  • Psychological disturbances
  • Depressed sperm and testosterone production
    breast development in males
  • Masculinization in women and children
  • Premature closure of bone growth centers

A Caution About Supplements and Drugs
  • Supplements taken to speed recovery from training
  • Creatine monohydrate
  • Chromium picolinate
  • Substances taken to increase training intensity
    and overcome fatigue
  • Amphetamines
  • Caffeine

A Caution About Supplements and Drugs
  • Substances taken to increase endurance
  • Erythropoietin
  • Darbepoetien
  • Substances taken to aid weight control
  • Diethylpropion, phentermine
  • Caffeine, PPA, ephedra
  • Dinitrophenol
  • Diuretics

Evaluating Dietary Supplements
  • Do you need a supplement at all?
  • Is the product safe and effective?
  • What studies have been done?
  • What has the research shown?
  • Can you be sure that the specific product is of
    high quality?

  • Chapter 5

  • Flexibility Defined as the range of motion
    (ROM) of a single joint or a group of joints. It
    is specific to each joint. The amount of
    movement is largely determined by the tightness
    of muscles, tendons, and ligaments that are
    attached to the joint.
  • Benefits
  • Reduce muscle soreness
  • Reduce muscle tension
  • Reduce risk of low back pain
  • Improve muscle performance
  • Improve posture
  • Improve muscle coordination
  • Reduce the risk of injury

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Types of Flexibility
  • Active (Dynamic) Flexibility The degree to
    which the force of a muscle contraction can move
    a joint. A muscle is stretched by a contraction
    of the opposing muscle. Involves movement.
    Dynamic shoulder flexibility would affect your
    ability to swing a golf club. Important for
    daily activities and sports.
  • Passive (Static) Flexibility Refers to the
    ability to assume and maintain an extended
    position at one end or point in a joints range
    of motion. It involves no muscle contraction.
    An outside force or resistance provided by
    yourself, a partner, gravity or a weight helps
    the joints move through their ROM. Easier to
    measure than dynamic flexibility and is usually
    how we refer to flexibility.

What Determines Flexibility?
  • Joint structurejoints vary in direction and
    range of movement
  • Joint capsules semielastic structures that give
    joints strength and stability but limit movement
  • Muscle elasticity and length
  • Collagen white fibers that provide structure
    and support
  • Elastin yellow fibers that are elastic and
  • Titin muscle filament with elastic properties

Muscle Elasticity and Length
Effect of Stretch on Connective Tissue
Factors That Affect Flexibility
  • Joint Structure and related connective tissue
    One cannot change the joint structure and the
    range of motion of each joint will vary. But,
    the length of the resting muscle fibers can be
  • Soft Tissue Muscle tissue, connective tissue,
    skin, scar tissue, fat tissue can all affect
  • Age Aging decreases the natural elasticity of
    the muscles, tendons and joints resulting in
    stiffness. Sedentary lifestyles, common with
    aging, also affect flexibility.
  • Gender The differences tend to be joint
    specific and do not always favor women, which is
    a common perception.
  • Muscle temperature Warmed muscles stretch
    better than cold muscles and are less prone to
  • Pregnancy Due to release of relaxin, there is a
    change in the elastic properties which improves
    muscle and joint flexibility.

  • FREQUENCY minimum of 2-3 days/week 5-7
    days/week may be better.
  • INTENSITY Slowly stretch warm muscles to the
    point of slight tension or mild discomfort.
  • TIME Hold the stretch for 10-30 seconds
    repeating 3- 5 times. Relax and breath.
  • TYPE Stretch the major muscle groups exercised.
    Refer to the end of the chapter for exercises.

Proprioceptive Neuromuscular Facilitation (PNF)
  • Most popular PNF stretching is the contract-relax
    stretching method, in which a muscle is
    contracted before it is stretched.
  • The muscle being stretched is held in an
    isometric contraction first, then passively
    stretched. This also works when the opposing
    muscle is contacted prior to the passive stretch.
  • Example Stretching the hamstring Contract the
    hamstrings, relax the hamstrings, contract the
    quadriceps, stretch the hamstrings.
  • PNF is an effective way to increase flexibility.
    Usually requires a partner. PNF protocol should
    include 4 repetitions of each stretch, 3-5

Static vs Ballistic Stretching
  • Static stretching is the preferred method of
    stretching. A stretch is held to the point of
    slight tension or mild discomfort, but not pain.
    This allows for the development and retention of
    muscular flexibility.
  • Ballistic (Bouncing) Stretching is the most
    dangerous of the stretching procedures. It may
    lead to muscle soreness or injury.

Stretching Techniques
A Flexibility Workout
The Lower Back
  • Low Back Pain has a direct relationship to
    lifestyle and wellness behaviors. Proper
    lifestyle choices can help prevent LBP.
    Sedentary lifestyles contribute to loss of
    muscular strength, endurance, and a limited ROM.
  • Low Back Pain is the number one physical
    complaint by individuals ages 25-60 in the U.S.
    Second most common ailment for job absenteeism
    for ages 30-60. It contributes for 25 of days
    lost for the entire work force.
  • LBP will affect 60-80 of the American and
    European population at some point.
  • 50 billion will be spent each year by government
    and industry for LBP (job absenteeism, disability
    payments, workers compensations, disability
    insurance, medical and legal fees)
  • Most pain occurs in the lumbar (lower) and sacral
    region because it bears the majority of your

Low-Back Health
  • Function of the spine
  • Provides structural support for the body
  • Surrounds and protects the spinal cord
  • Supports body weight
  • Serves as attachment site for muscles, tendons,
  • Allows movement of neck and back in all directions

Skeletal System
Structure of the Spine
  • 7 cervical vertebrae in the neck
  • 12 thoracic vertebrae in the upper back
  • 5 lumbar vertebrae in the lower back
  • 9 vertebrae at the base of the spine fused into
    the sacrum and the coccyx (tailbone)

Structure of the Spine
  • Vertebrae consist of a body, an arch, and several
    bony processes
  • Intervertebral disks elastic disks located
    between adjoining vertebrae consist of a gel-
    and water-filled nucleus surrounded by fibrous
    rings serve as shock absorbers
  • Nerve roots base of pairs of spinal nerves that
    branch off the spinal cord

Vertebrae and Intervertebral Disk
Core Muscle Fitness
  • Core muscles include those in the abdomen, pelvic
    floor, sides of the trunk, back, buttocks, hip,
    and pelvis
  • Core muscles stabilize the spine and help
    transfer force between the upper body and lower
  • Lack of core muscle fitness can create an
    unstable spine and stress muscles and joints
  • Whole body exercises and exercises using free
    weights or stability balls all build core muscle

Causes of LBP
  • The most common cause of LBP
  • is physical inactivity!
  • Poor posture
  • Faulty body mechanics
  • Stressful living and working habits
  • Weak musculature especially
  • the abs
  • Poor flexibility in the lower back
  • and hamstrings
  • Smoking

Prevention of LBP
  • Exercise regularly to strengthen your back and
    abdominal muscles.
  • Lose weight, if necessary, to lessen strain on
    your back.
  • Avoid smoking (which increases degenerative
    changes in the spine).
  • Lift by bending at your knees, rather than the
    waist, using leg muscles to do most of the work.
  • Receive objects from others or platforms near to
    your body, and avoid twisting or bending at the
    waist while handling or transferring it.

Prevention of Low Back Pain (cont.)
  • Avoid sitting, standing, or working in any one
    position for too long.
  • Maintain a correct posture (sit with your
    shoulders back and feet flat on the floor, or on
    a footstool or chair rung. Stand with head and
    chest high, neck straight, stomach and buttocks
    held in, and pelvis forward).
  • Use a comfortable, supportive seat while driving.
  • Use a firm mattress, and sleep on your side with
    knees drawn up or on your back with a pillow
    under bent knees.
  • Try to reduce emotional stress that causes muscle
  • Be thoroughly warmed-up before engaging in
    vigorous exercise or sports.
  • Undergo a gradual progression when attempting to
    improve strength or athletic ability.

Treatment of Low Back Pain
  • Physical Activity Only 1 of all back patients
    need surgery. Most rehabilitation and prevention
    is lifestyle related.
  • Maintain a normal weight. Excess abdominal
    weight can lead to lordosis and poor posture.
  • Participate in regular aerobic exercise.
  • Participate in regular muscular strength and
    endurance activities, especially for the
    abdominal and back regions.
  • Incorporate lower back and hamstring flexibility
    exercises. Work all the planes of motion.

Managing Acute Back Pain
  • Sudden back pain usually involves tissue injury
  • Symptoms Pain, muscle spasms, stiffness,
  • Treatment
  • Ice, then heat
  • OTC medication (ibuprofen or naproxen)
  • Moderate exercise

Managing Chronic Back Pain
  • Considered chronic if lasts longer than 3 months
  • Symptoms Stabbing or shooting pain, steady ache
    accompanied by stiffness, pain that is localized
    or that radiates to other parts of the body
  • Treatment Many options, including medication,
    exercise, physical therapy, massage, acupuncture,
    education, and surgery

Tip of the Day
  • Results in training occur with consistency and
    effort a lifestyle habit!