Regaining Muscular Strength, Endurance and Power

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Regaining Muscular Strength, Endurance and Power
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Regaining Strength, Endurance Power

• Critical to maintain and improve in each area in
  order to achieve competitive fitness levels and
  return athlete to functional level following
  injury
• Muscular Strength
• Ability to generate force against some resistance
• Important to maintain normal levels for normal
  healthy living
• Imbalance or weakness can impair normal function
• Muscular Endurance
• Ability to perform repetitive muscular
  contractions against some resistance
• Power
• Ability to generate force quickly
• Combination of strength speed
• Performance is limited without power

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Types of Skeletal Muscle Contraction

• Isometric Contraction
• Contraction that produces m. tension but no
  change in m. length
• Concentric Contraction
• Contraction that causes m. shortening while
  tension increases to overcome some resistance
• Eccentric Contraction
• Resistance is greater than the muscular force
  being produced muscle lengthens while producing
  tension
• Econcentric contraction
• Controlled concentric eccentric contraction of
  same muscle over 2 separate joints
• Hamstring and rectus femoris of quadriceps
• Strength training must focus on functioning of
  muscle
• Multi-planar
• Various contractions - functionally

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Factors That Determine Levels of Strength,
Endurance Power

• Size of Muscle
• Proportional to cross-sectional diameter of
  muscle fibers
• Increased cross-sectional area increased
  strength and force production
• Hypertrophy
• Increase in muscle size
• Atrophy
• Decrease in muscle size
• Number of Muscle Fibers
• Strength is a function of the number and diameter
  of muscle fibers
• Number of fibers is inherited characteristic

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• Neuromuscular Efficiency
• Strength is directly related to efficiency of the
  neuromuscular system
• Initial increases in strength during first 8-10
  weeks are attributed to neuromuscular efficiency
• Efficiency enhanced strength in 3 ways
• Increase of motor unit recruitment
• Increase in firing rate of each motor unit
• Enhance synchronization of motor unit firing
• Age
• Men women increase strength throughout puberty
  adolescence
• Peaks at age 20-25
• After age 25, max strength declines 1 annually
• Decline is related to physical activity
• Able to retard decline in performance through
  activity

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• Biomechanical Considerations
• Position of tendon attachment
• Relative position of tendon attachment to fulcrum
  of the joint
• The closer the tendon is to resistance, the
  greater the force produced
• Change in attachment will alter force generating
  capabilities
• Length-Tension Relationship
• Length of muscle determines tension that can be
  created
• Varying lengths will produce varying tensions
• Determined by overlap of actin-myosin filaments
• Overtraining
• Imbalance between exercise and recovery
• Training exceeds physiological and psychological
  capacity of individual
• Can have negative effect on strength training
• May result in psychological or physiological
  breakdown
• Injury, illness, and fatigue can be indicators

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Fast-Twitch vs. Slow Twitch

• Slow Twitch Fibers
• Type I or slow oxidative (SO)
• More resistant to fatigue
• Time required to generate force is greater in
  slow twitch fibers
• Primarily associated with long duration, AEROBIC
  activities
• Fast Twitch Fibers
• Type IIa (fast oxidative glycolytic- FOG)
• Moderately resistant to fatigue
• Type IIb (fast glycolytic - FG)
• Fatigues rapidly true fast twitch
• Type IIx fatigue resistant with force capacity
  (altxltb)
• Produce quick, forceful contractions
• Short-term, high intensity activities, ANAEROBIC
  activities

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• Ratio in Muscle
• Both fiber types exist in individual muscles
• Ratio varies by muscle and by individual
• Postural muscles ? primarily type I fibers
• Power, explosive strength muscles ? type II
  fibers
• Genetically determined
• Large role in determining ability for a given
  sport activity
• Fiber changes due to training
• Enhanced metabolic capabilities through specific
  training

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Physiology of Strength Development

• Muscle Hypertrophy 3 theories
• Hyperplasia ? in number of muscle fibers
• Genetically determined does not seem to
  increase with training
• Evidence exists of fibers splitting conducted
  in animals
• Hypothesized increased number of capillaries
  partially correct
• No new capillaries
• Increase in dormant capillary activity to meet
  needs of muscle
• Increased size and number of myofilaments
• Actin (thin) and Myosin (thick)
• When muscle is stimulated to contract,
  cross-bridges pull myofilaments closer which
  shortens the muscle, produces movement at joint
  that muscle crosses
• Reversibility adaptations of muscle due to
  training can begin to reverse within 48 hours of
  removing training

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Other Physiological Adaptations to Resistance
Exercise

• Strength of non-contractile structures
• Tendons and ligament increase
• Increased bone-mineral content
• Improved oxygen uptake
• If resistance training is high enough to elicit a
  cardiovascular response/adaptation
• Increased metabolic enzymes

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Techniques of Resistance Training

• Overload Principle
• To improve strength, muscle must be worked at a
  level higher than it is accustomed to
• Muscle will maintain strength if it is trained
  against a consistent resistance that it is
  accustomed to
• Existence of current strength will result in
  increased muscle endurance
• Effective training requires a consistently
  increasing effort against progressively more
  resistant loads
• In rehabilitation, rate of progression is
  determined by athletes response to specific
  exercise
• Be mindful of pain when dealing with progression

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• Isometric Exercise
• Capable of increasing muscle strength at specific
  joint angles
• Exercise with no change in muscle length
• May produce spikes in systolic blood pressure
• Could cause life-threatening cardiovascular
  accident
• To reduce this event to occur - REMIND the
  person to breath
• Widely used in rehabilitation
• Attempt to use positional or functional exercise
  work at multiple angles throughout the range if
  possible
• Contractions should be held for 10 seconds at
  frequency of 10 or more per hour
• Utilized to enhance lift or activity at sticking
  point

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• Progressive Resistive Exercise (PRE)
• Exercises that work through a full range of
  motion
• Isotonic or isodynamic contractions
• Most popular commonly used technique
• Concentric vs. Eccentric
• Greater force can be generated due to lower
  number of motor units recruited allowing other
  motor units to be recruited to generate increased
  force
• Oxygen use is much lower with eccentrics
• Efficiency of eccentric exercise is higher than
  concentric exercise
• Needs of the body acceleration and deceleration
• Must be able to control body movements
  deceleration and eccentrics allows for this
  control

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• Free Weights vs. Exercise Machines
• Advantages disadvantages for both
• Machines
• Safety easy to use
• Constraints on motion generally single plane of
  motion
• Free weights
• Do not restrict motion
• Incorporates certain level of neuromuscular
  control
• Surgical Tubing (Theraband) or Exercise Band
• Allow for motion in multiple planes
• Ability to perform more functional movement
• Can be utilized with PNF plyometrics
• Variable Resistance
• Change in force required at different angles to
  move a particular resistance
• Greatest when joint is at 90 degrees
• Accommodating resistance or variable resistance
  equipment changes resistance at different points
  in range

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• Progressive Resistive Exercise Techniques (PRE)
• Terminology
• Repetitions
• Repetition maximum (RM)
• Set
• Intensity
• Recovery period
• Frequency
• Recommended Techniques of Resistance Training
• Must consider 4 areas
• Amount of weight to be used
• Number of repetitions
• Number of sets
• Frequency of training

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• The healing process must dictate the program!
• Intensity is key
• Multiple potential routines
• Single set 1 set 8-12 reps at a slow speed
• Tri-sets 3 exercises for 1 muscle group, 2-4
  sets with no rest
• Multiple sets 2-3 warm-up sets with
  progressively increasing resistance followed by
  several sets at the same resistance
• Superset multiple exercises, 1 set of 8-10
  repetitions or 1 or 2 exercises, with multiple
  sets of 8-10 repetitions
• Pyramid multiple sets decreasing repetitions
  and increasing resistance
• Split routine Workouts exercise different
  groups of muscles on different days
• Circuit Training
• Group of exercise (flexibility, callisthenic,
  strength, brief aerobic)
• Used to increase strength or endurance
• Move from one station to the next, performing
  exercise for a given time period or number of
  repetitions

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Resistance Training Techniques Used in
Rehabilitation

• DeLormes method
• Based on repetition maximum of 10
• Designed for early rehab
• Designed for beginning rehab
• Introduced PRE progressive loading
• Builds in warm-up period
• MacQueens method
• Utilizes varying sets for beginning/intermediate
  advanced
• Set of 10 RM

• Oxford method
• Used during early, intermediate advanced levels
  of rehabilitation
• Percentages of 10 RM
• Diminishes resistance as muscle fatigues
  regressive load
• Sanders program
• Utilized in advanced stages of rehabilitation
• Utilizes percentages of body weight

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• Knight (DAPRE)
• Daily Adjustable Progressive Resistive Exercise
• Adjusted based on individuals progress
• Based on 6 RM working weight
• Berger
• Adjusts within individuals limitations
• Should allow for 6-8 RM repetitions on 60-90
  seconds
• Must be able to achieve 3 sets of at least 6 RM
  and no more than 8 RM
• Increases occur in 10 increments

• For rehabilitation
• Base program on pain and healing process
• Should be performed daily early on
• Reduce workout to every other day as progress is
  made

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Isokinetic Exercise

• Involves muscle contractions where length change
  of muscle is set at a constant velocity
• Maximal resistance throughout the range of motion
• Variety of machines/manufacturers are available
• Can be used with eccentrics concentric exercise

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• Isokinetics as a Conditioning Tool
• Maximal effort for maximal strength gains
• Dynamometer will move at a set speed whether
  maximal or half of maximal effort is put forth
• Athlete can cheat with machine and not put forth
  the effort
• Not cost effective
• Isokinetics in Rehabilitation
• Gained popularity in rehabilitation during the
  1980s
• Provide objective means of athlete/patient
  evaluation
• Training at fast vs. slow speeds
• Functional speeds

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Plyometric Exercise

• Encompass a rapid stretch of muscle eccentrically
  followed by a rapid concentric contraction to
  facilitate the development of explosive power
• Greater stretch relative to resting length
  greater resistance muscle can overcome
• Speed of stretch is emphasized over magnitude
• Used to develop eccentric control of dynamic
  movements
• Exercises should be performed technically correct

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Core Stabilization Strengthening

• Fundamental component of rehabilitation
• Strengthening of core (lumbo-pelvic complex)
• Used to
• Improve dynamic postural control
• Ensure appropriate muscular balance joint
  movement about the core
• Improve neuromuscular efficiency and expression
  of dynamic functional movement
• Provide optimal stabilization of kinetic chain
  and balanced muscular functioning throughout the
  chain

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Open vs. Closed Kinetic Chain Exercises

• Anatomical functional relationships that exist
  in the upper and lower extremity
• Open kinetic chain
• May be needed when lower extremity is to be
  non-weight-bearing
• Closed kinetic chain
• Useful in rehabilitation
• Most activities call for weight bearing of foot
  or hand in some capacity
• May be more functional than open chain activities
  in some instances

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Training for Muscular Strength vs. Muscular
Endurance

• Strength and endurance are closely related
• As one improves, the tendency is for the other to
  do the same
• For strength development
• Heavier weight and low repetitions should be used
• Endurance training
• Lighter weight and high repetitions (10-15) are
  suggested

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Resistance Training Differences Between Males
Females

• Females tend not to develop significant muscle
  bulk due to reduced levels of testosterone
• While bulk generally does not increase muscle
  tone will increase through training in females
• Gains are primarily neuromuscularly related
  tend to plateau for females

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• Males tend to continue developing strength
  through increased bulk following the
  neuromuscular strength gains
• Strength/Body Weight Ratio
• Females tend to have a lower ratio due to higher
  levels of body fat
• Absolute strength differences
• Reduced when body size composition are compared
• Leg strength can actually be stronger in females
  with upper extremity strength greater in males

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Resistance Training in Young Athletes

• Same principles can be applied to young athletes
• Much debate sociologically physiologically
• If properly supervised, young athletes can make
  improvements in all areas of fitness
• Pre-pubescent child will experience gains in
  muscle strength without muscle hypertrophy
• Resistive exercise should be integrated into a
  young athletes rehabilitation
• Close instruction supervision is necessary
• Base on extent of maturation critical to
  effectiveness

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Resistance Training in Older AdultsKisner
Colby, p. 125
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Specific Resistive Exercises Used in
Rehabilitation

• Goal of program
• To regain and possibly increase specific muscle
  strength
• Increase efficiency of movement
• Variety of exercise modes can be utilized to
  achieve goals

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• Isometric Exercise
• Used during initial stages of rehabilitation
• Useful when training through a full range of
  motion is contraindicated
• Serve to increase static strength, decrease
  atrophy, create muscle pump to reducing edema
• Progressive Resistive Exercise (PRE)
• Most commonly used strengthening technique
• Incorporates free weights, machines and tubing
• Utilizes isotonic contractions (concentric and
  eccentric contractions)

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• Isokinetic Exercise
• Incorporated in later stages of rehabilitation
• Uses fixed speeds with accommodating resistance
• Provides maximal resistance through full range of
  motion
• Commonly used as criteria for return of athlete
  to functional activity

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• Plyometric Exercise
• Generally incorporated in later stages of
  rehabilitation
• Relies on a quick eccentric stretch to facilitate
  a subsequent concentric contraction
• Encourages dynamic movements associated with
  power
• Due to the need to generate power in athletic
  activities, it is critical to incorporate it
  within a the rehabilitation process

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• Core Stabilization
• Essential for functional strength
• Core functions to dynamically stabilize the
  kinetic chain
• Core strength enables distal segments to function
  optimally and efficiently during force and power
  generation

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References

• Kisner, C. Colby, L. (2002). Therapeutic
  Exercise Foundations Techniques, 4th ed.