Download Musculoskeletal Health

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.
CHICKEN
vs
DUCK
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.
Muscles
• Weight training causes the SIZE of
the individual muscle fibers to
increase by increasing the number
of myofibrils.
• HYPERTROPHY– the development
of large muscle fibers.
• 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 100’s of fibers in each unit.
The number of motor units recruited depends on the
amount of strength required.
Small weight → Few motor units
Large weight → More motor units
Strength training improves the body’s ability to recruit
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
BENEFITS OF RESISTIVE
TRAINING
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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
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 contraction
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 trained.
• 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 them!
– 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
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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 healing.
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 strength.
• 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 MS&E 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
cell.
• Gender
– Women will not experience as much hypertrophy as men will.
This is due to lower levels of testosterone.
• 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 reversible.
FITT PRINCIPLES
• 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 occur.
For strength, may use 80% of 1RM for 1-8 repetitions.
Higher amount of weight → Less Repetitions
For endurance, use 40-60% of 1RM for 15-20 repetitions.
Lower amount of weight → More Repetitions
For general fitness, use 70% of 1 RM for 10-12 repetitions.
Training for Strength versus
Training for Endurance
FITT Principle for Strength
Training
FITT PRINCIPLES
• “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
repetitions.)
• 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.
FITT PRINCIPLES
• Type or Mode of Exercise – For overall fitness include
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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
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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 result.)
• SUPER SLOW – Both concentric and eccentric movements are
slowed down to achieve maximum contractions.
Making Progress
• To start: Choose a weight with which you
can do 8–12 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 workouts
• 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.
DON’T HOLD BREATH.
• 3. Use spotters with free weights
in any exercise where you could
lose control of the weight.
• 4. Always use lock-collars on bar
ends so plates don’t fall off.
• 5. Use proper lifting techniques
Machines vs Free Weights
• Machines
~Safe
~Convenient
~Easy to Use
~Don’t need spotter
~Rapid, effortless change of
resistance
~Controlled range of motion
~Provide both positive and
negative resistance
~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
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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
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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?
FLEXIBILITY
AND LOW
BACK HEALTH
Chapter 5
FLEXIBILITY
• 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
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 joint’s 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 structure—joints 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
flexible
– Titin = muscle filament with elastic
properties
Muscle Elasticity and Length
Effect of Stretch on
Connective Tissue
Factors That Affect Flexibility
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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 developed.
Soft Tissue – Muscle tissue, connective tissue, skin, scar tissue, fat tissue
can all affect flexibility.
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 injury.
Pregnancy – Due to release of relaxin, there is a change in the elastic
properties which improves muscle and joint flexibility.
FITT PRINCIPLES
• 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 days/week.
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, worker’s
compensations, disability insurance, medical and legal fees)
• Most pain occurs in the lumbar (lower) and sacral region because
it bears the majority of your weight.
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, ligaments
– Allows movement of neck and back in all
directions
Skeletal
System
Structure of the Spine
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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
• 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 body
• 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 fitness
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
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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 tension.
• 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, inflammation
• 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!