Download Muscle Contractions

Chapter 4: Preventing
Injuries Through
Fitness Training
• Fitness is critical for performance and
injury prevention
• Improper conditioning is a major
cause in sports related injuries
• Areas of concern:
– Flexibility
– Muscular strength, endurance, power
– Cardiorespiratory endurance
• Coaches need to develop programs
that focus on injury prevention and
performance enhancement
Periodization in Training and
Conditioning
• Traditional seasons no longer exist for
serious athletes
• Periodization
– Achieve peak performance
– Decrease injuries and overtraining
– Program that spans various seasons
– Modify program relative to athlete’s
needs
Year Round Training Cycle
• Complete training cycle
• Seasonal approach based on
preseason, in-season, and off-season
• Changes in intensity, volume,
specificity of training occur in order to
achieve peak levels of fitness for
competition
• Broken into periods or phases (lasting
weeks or months)
Periods or Phases
• Transition period:
– Follows last competition (early off-season)
– Unstructured (escape rigors of training)
• Preparatory period:
– Off-season
– Hypertropy/endurance phase (Low intensity
with high volume)
• Allows for development of endurance base
• Lasts several weeks to 2 months
• Preparatory period (continued)
– Strength Phase
• Intensity and volume increase to moderate levels
– Power Phase (High intensity/ pre-season)
• Volume is decreased to allow adequate recovery
• Competition period:
– May last a < week or several months for
seasonal sports
– High intensity, low volume, skill training
sessions
– May incorporate weekly training cycles (1-7
days)
• Designed to ensure peak on days of competition
Cross Training
• Training for a sport with substitutions
of alternative activities (carryover
value)
• Useful in transition and preparatory
periods
• Variety to training regimen
• Should be discontinued prior to
preseason as it is not sport-specific
Principles of Conditioning
and Training
• Warm-up/Cooldown
• Intensity
• Specificity
• Motivation
• Individuality
• Overload and SAID
principle
• Relaxation/
Minimize Stress
• Consistency/
routine
• Safety
• Progression
Warm-up
• Precaution against unnecessary musculoskeletal
injury and soreness
• May enhance certain aspects of performance
• Prepares body physiologically for physical work
• Stimulates cardiorespiratory system, enhancing
circulation and blood flow to muscles
• Increases metabolic processes, core temperature,
and muscle elasticity
General
– Activities which bring a general warming
to the body(break a sweat)
– Not related to sport
Specific
– Specific to sport
– Stretching, jogging, running, throwing,
catching
Should last 10-15 minutes resulting in
effects that will last 45 minutes
Cool-down
• Essential component of workout
• Bring body back to resting state
• 5-10 minutes in duration
• Often ignored
• Decreased muscle soreness following
training if time used to stretch after
workout
Why is it important to have
good flexibility?
• Ability to move a joint(s) smoothly
through a full range of motion (ROM)
• Decreased ROM results in:
– Decreased performance capabilities
– Uncoordinated/awkward movements
– Predisposes athlete to injury
• Good flexibility is essential for successful
physical performance
• Recommended by athletic trainers to
prevent injury
Factors That Limit Flexibility
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Bony structures
Tissue approximation
Excessive fat
Muscle and tendon lengths
Connective tissue
Scarring and contractures
Skin
Range of Motion
(ROM)
• Active range of motion = dynamic flexibility
– Ability to move a joint with little resistance
• Passive range of motion = static flexibility
– Motion of joint to end points without muscle
contraction
• Must be able to move through unrestricted
range
• Must have elasticity for additional stretch
encountered during activity
Agonist vs. Antagonist
Muscles
• Joints are capable of multiple movements
• Example:
– Quadriceps will extend knee with contraction
– Hamstrings will stretch during extension
– Quads (muscle producing movement) referred to as
agonist
– Muscle undergoing stretch referred to as antagonist
– Agonist and antagonist work together to produce
smooth coordinated movements
Stretching Techniques
Ballistic
– Bouncing movement in which repetitive
contractions of agonist work to stretch
antagonist muscle
– While effective in improving flexibility,
caution should be exercised
– Possible soreness (soccer example)
Static stretching
– Passively stretching
– 20-30 second hold = optimal
– Go to point of pain and back off and hold
for 30 seconds (3 to 4 times)
– Controlled, less chance of injury
– Not dynamic
– Should precede ballistic stretching
Proprioceptive Neuromuscular
Facilitation
– Contract-relax
– Hold-relax
– Ten second push, ten second relax
– Best technique to improve flexibility
– Technique that involves combination of
alternating contractions and relaxation
of both agonist and antagonists
Assessment of Flexibility
• Various devices have been designed to
accommodate joint sizes and
complexities of movement
• Goniometer most widely used device
• Can also utilize the following tests:
– Trunk hip flexion test
– Trunk extension test
– Shoulder extension test
Is there a relationship
between strength and
flexibility?
• Co-exist
• Muscle bound = zero flexibility
• Strength training will provide
individual with ability to develop
dynamic flexibility through full range
of motion
• Develop more powerful and
coordinated movements
Flexibility, Muscular
Strength,
Endurance, and
Power
Muscle Strength, Power, and
Endurance
Strength: ability to generate force
against resistance
Muscular endurance: repetitive
muscular contractions (increase
strength = increase endurance)
Power: the relationship between
strength and time
Muscle Contractions
• Isometric contraction
– No length change occurs during contraction
• Isotonic contraction
– Concentric- shortening of muscle with
contraction in an effort to overcome more
resistance
– Eccentric - lengthening of muscle with
contraction because load is greater than force
being produced
– Both are considered dynamic movements
Factors that Determine
Levels of Muscular Strength
• Size of muscle:
– Function of diameter and of muscle fibers
– Hypertrophy vs. Atrophy
• Number of muscle fibers
• Neuromuscular efficiency
– Initial gains are due to increased efficiency
• More effectively engage specific motor units
• Biomechanical factors
– Bones and muscles = Levers and pulleys
• Fast-Twitch vs. Slow-Twitch Muscle Fibers
• Motor units with distinct metabolic and
contractile capability
Individual make-up
– Muscles contain both types of fibers
– Muscle functioning impacts ratios (postural vs.
powerful movement)
– Genetically determined
• Slow twitch (Type I):
– Generally major constituent of postural muscles
• Fast twitch (Type II)
– High force in short amount of time
– Produce powerful movements
• Levels of Physical Activity
– Will influence increase/decrease in
muscle strength
– Also impacts cardiorespiratory fitness,
flexibility and increases in body fat
• Overtraining
– Psychological and physiological
breakdown
– Signs
• Apathy, loss of appetite, staleness, declines in
performance, weight loss, inability to sleep
– Prevent through appropriate training
protocol, proper diet, and rest
What physiological changes
occur to cause increased
strength?
• Multiple theories of muscle
hypertrophy
• Primary explanation of muscle
hypertrophy:
– Increase in protein myofilament number
and size
• Continued need for additional
research
Core Stabilization Training
• Core refers to muscles that make up center of
body
– Low back, pelvis, hips, abdomen
• Works to stabilize body enabling muscles of
extremity to function optimally
• Weak core is a fundamental problem of
inefficient movements = injury
• Program targets strength, neuromuscular
control, power, and endurance of the core
• Program will stress multiple planes and
incorporate various resistance techniques
Techniques of Resistance
Training
• Progressive resistance exercise
• Overload principle must be applied
• Must work muscle at increasingly
higher intensities to enhance strength
over time
• If intensity of training does not
increase, but training continues,
muscle strength will be sustained
Isometric Exercise
• Contraction where muscle length
remains unchanged
• Muscle contraction that lasts 10
seconds and should be perform 5-10
times/daily
• Pro: quick, effective, cheap, good for
rehab
• Con: only works at one point in ROM,
produces spiking of blood pressure
due to Valsalva maneuver
• Concentric and eccentric training
should be incorporated for greatest
strength improvement
• Concentric phase of lift should last 1-2
seconds; eccentric phase 2-4 seconds
• Variations exist between free and
machine weight lifting
– Motion restrictions, levels of muscular
control required, amount of weight that
can be lifted
– Equipment design, varying resistances
Progressive Resistance
Exercise Techniques
• Terminology associated with weight
training
– Repetitions
– Repetition maximum
– One repetition maximum
– Set
– Intensity
– Recovery period
– Frequency
• When training should be able to
perform 3 sets of 6-8 repetitions
• Increases should occur in increments
of 10%
• 1 RM can be utilized to measure
maximum amount of weight that can
be lifted - must be very careful
• Training of a particular muscle group
should occur 3-4 times per week (not
on successive days)
Muscular Endurance vs.
Strength
• Training for endurance enhances
strength and vice versa
• Training for strength should involve
lower repetitions at heavier weight
• Training for endurance requires lower
weight at 12-15 repetitions
Open vs. Closed Kinetic
Chain Exercises
• Anatomical functional relationship for
upper and lower extremities
• OKC
– When foot or hand are not in contact
with the ground or supporting surface
• CKC
– Foot or hand are weight bearing
– Widely used = more functional
Isokinetic Training
• Muscle contraction at a constant velocity
• Maximal and constant resistance
throughout the full range of motion
• Maximal effort = Maximal strength gains
• Rehab
• Never widely used in strength training
• Losing popularity in rehabilitation
settings
Circuit Training
• Combination of exercise stations
• 8 - 12 stations, 3 times through
• Design for different training goals
– Flexibility
– Calisthenics
– Aerobic exercise
Plyometric Exercise
• Rapid stretch, eccentric contraction
followed by a rapid concentric contraction
to create a forceful explosive movement
• Rate of stretch vs. magnitude
• Jumps, bounds, medicine ball throws
• Very technical training - skills must be
learned with appropriate technique
• Often develop muscle soreness as a result
of extensive eccentric loading
Training for the Female
Athlete
• Critical for female athlete
• Significant hypertrophy is related to
testosterone present within body
• Remarkable gains are experienced
initially due to enhanced nervous
system and muscle interaction
(efficiency-not muscle bulk)
• Following initial gains, plateau
occurs, with females
• Males tend to continue to increase
strength with training
• Critical difference is the ratio of
strength to body fat
– Females have reduced strength to body
weight ratio due to higher percentage of
body fat
– Ratio can be enhanced through weight
training and decrease in body fat
percentage/increased lean weight
Cardiorespiratory
Endurance
• Perform whole body activities for
extended period of time
• Performance vs. fatigue vs. injury
• Aerobic exercise
– Low intensity exercise that can be
sustained for a long period of time
• Anaerobic exercise
– Activity where intensity is so high that
demand for oxygen is greater than body’s
ability to deliver
• System’s
four components
– Heart
– Lungs
– Blood vessels
– Blood
• Improvements in endurance are the
results of improvements in these 4
components
Impact on Heart
• Main pumping mechanism
• Increase exercise = increased oxygen
requirement = increase heart pumping
• Heart able to adapt through increases
in heart rate and stroke volume which
will enhance overall cardiac output
• Oxygenation of blood
What determines how
efficiently the body is using
oxygen?
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Aerobic capacity = VO2max
More active = higher capacity
Average value = 45-60 ml O2/min/kg
Increases in intensity require higher levels
of oxygen consumption
• Inherit certain range of maximum aerobic
capacity (genetics)
– Dependent on activity levels
– Also impacted by muscle fiber types
Maximum Aerobic Capacity
• Most accurate techniques must be performed
in a laboratory setting
– Treadmill, bicycle ergometer
– Monitor heart rate and gas exchange at
particular workload
• Generally utilize heart rate to estimate
percentage of maximum aerobic capacity
– Indirect method
– Heart rate and aerobic capacity have linear
relationship
Types of Training for
Cardiorespiratory Endurance
• Continuous
– Mode (type of exercise) - must be aerobic in
nature
– Frequency (at least 3 times/week)
– Duration (at least 20 minutes)
– Intensity (monitor intensity as % of heart
rate or perceived exertion)
• Training heart rate – target heart rate
Maximum HR = 220 - Age
• Karvonen formula (60% HR Max)
– Target HR=Resting HR+(.6 [Max HR – Resting HR)]
• Interval training
– Intermittent activities involving periods
of intense work and active recovery
– Must occur at 60-80% of maximal heart
rate
– Allows for higher intensity training at
short intervals over an extended period
of time
– Most anaerobic sports require short burst
which can be mimicked through interval
training
• Fartlek training
– Cross-country running that originated in
Sweden
– Speed play
– Similar to interval training in that
activity occurs over a specific period of
time but pace and speed are not specified
– Consists of varied terrain which
incorporates varying degrees of hills
– Dynamic form of training
– Must elevate heart rate to minimal levels
to be effective
– Popular form of training in off-season