Download Regaining Muscular Strength, Endurance and Power

Regaining Muscular
Strength, Endurance and
Power
Regaining Strength, Endurance & Power
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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
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Muscular Endurance
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Ability to generate force against some resistance
Important to maintain normal levels for normal healthy living
Imbalance or weakness can impair normal function
Ability to perform repetitive muscular contractions against some
resistance
Power
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Ability to generate force quickly
Combination of strength & speed
Performance is limited without power
Types of Skeletal Muscle Contraction
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Isometric Contraction
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Concentric Contraction
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Resistance is greater than the muscular force being produced &
muscle lengthens while producing tension
Econcentric contraction
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Contraction that causes m. shortening while tension increases to
overcome some resistance
Eccentric Contraction
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Contraction that produces m. tension but no change in m. length
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
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Multi-planar
Various contractions - functionally
Factors That Determine Levels of
Strength, Endurance & Power
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Size of Muscle
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Proportional to cross-sectional diameter of muscle
fibers
Increased cross-sectional area = increased strength
and force production
Hypertrophy
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Atrophy
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Increase in muscle size
Decrease in muscle size
Number of Muscle Fibers
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Strength is a function of the number and diameter of
muscle fibers
Number of fibers is inherited characteristic
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Neuromuscular Efficiency
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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
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Increase # of motor unit recruitment
Increase in firing rate of each motor unit
Enhance synchronization of motor unit firing
Age
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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
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Position of tendon attachment
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Relative position of tendon attachment to fulcrum of the joint
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Change in attachment will alter force generating capabilities
Length-Tension Relationship
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The closer the tendon is to resistance, the greater the force
produced
Length of muscle determines tension that can be created
Varying lengths will produce varying tensions
Determined by overlap of actin-myosin filaments
Overtraining
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Imbalance between exercise and recovery
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Training exceeds physiological and psychological capacity of
individual
Can have negative effect on strength training
May result in psychological or physiological breakdown
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Injury, illness, and fatigue can be indicators
Fast-Twitch vs. Slow Twitch
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Slow Twitch Fibers
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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
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Type IIa (fast oxidative glycolytic- FOG)
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Type IIb (fast glycolytic - FG)
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Moderately resistant to fatigue
Fatigues rapidly – true fast twitch
Type IIx – fatigue resistant with force capacity (a<x<b)
Produce quick, forceful contractions
Short-term, high intensity activities, ANAEROBIC activities
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Ratio in Muscle
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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
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Large role in determining ability for a given sport activity
Fiber changes due to training
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Enhanced metabolic capabilities through specific training
Physiology of Strength Development
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Muscle Hypertrophy – 3 theories
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Hyperplasia –  in number of muscle fibers
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Hypothesized increased number of capillaries – partially
correct
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No new capillaries
Increase in dormant capillary activity to meet needs of muscle
**Increased size and number of myofilaments
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Genetically determined & does not seem to increase with training
Evidence exists of fibers splitting – conducted in animals
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
Other Physiological Adaptations to
Resistance Exercise
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Strength of non-contractile structures
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Improved oxygen uptake
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Tendons and ligament increase
Increased bone-mineral content
If resistance training is high enough to elicit a
cardiovascular response/adaptation
Increased metabolic enzymes
Techniques of Resistance Training
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Overload Principle
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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
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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
athlete’s response to specific exercise
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Be mindful of pain when dealing with progression
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Isometric Exercise
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Capable of increasing muscle strength at specific joint
angles
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May produce spikes in systolic blood pressure
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Could cause life-threatening cardiovascular accident
To reduce this event to occur - REMIND the person to breath
Widely used in rehabilitation
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Exercise with no change in muscle length
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)
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Exercises that work through a full range of motion
Isotonic or isodynamic contractions
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Most popular & commonly used technique
Concentric vs. Eccentric
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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
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Advantages & disadvantages for both
Machines –
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Free weights –
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Do not restrict motion
Incorporates certain level of neuromuscular control
Surgical Tubing (Theraband) or Exercise Band
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Safety & easy to use
Constraints on motion & generally single plane of motion
Allow for motion in multiple planes
Ability to perform more functional movement
Can be utilized with PNF & plyometrics
Variable Resistance
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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)
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Terminology
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Repetitions
Repetition maximum (RM)
Set
Intensity
Recovery period
Frequency
Recommended Techniques of Resistance Training
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Must consider 4 areas
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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
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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
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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
Resistance Training Techniques
Used in Rehabilitation
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DeLorme’s method
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Based on repetition
maximum of 10
Designed for early rehab
Designed for beginning
rehab
Introduced PRE –
“progressive loading”
Builds in warm-up period
MacQueen’s method
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Utilizes varying sets for
beginning/intermediate &
advanced
Set of 10 RM
Oxford method
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Used during early,
intermediate & advanced
levels of rehabilitation
Percentages of 10 RM
Diminishes resistance as
muscle fatigues –
“regressive load”
Sander’s program
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Utilized in advanced
stages of rehabilitation
Utilizes percentages of
body weight
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Knight (DAPRE)
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Daily Adjustable
Progressive Resistive
Exercise
Adjusted based on
individual’s progress
Based on 6 RM working
weight
Berger
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Adjusts within individual’s
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
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For rehabilitation
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Base program on pain
and healing process
Should be performed
daily early on
Reduce workout to
every other day as
progress is made
Isokinetic Exercise
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Involves muscle contractions where length
change of muscle is set at a constant velocity
Maximal resistance throughout the range of
motion
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Variety of machines/manufacturers are available
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Can be used with eccentrics & concentric exercise
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Isokinetics as a Conditioning Tool
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Maximal effort for maximal strength gains
Dynamometer will move at a set speed whether
maximal or half of maximal effort is put forth
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Athlete can cheat with machine and not put forth the effort
Not cost effective
Isokinetics in Rehabilitation
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Gained popularity in rehabilitation during the 1980’s
Provide objective means of athlete/patient evaluation
Training at fast vs. slow speeds
Functional speeds
Plyometric Exercise
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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
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Speed of stretch is emphasized over magnitude
Used to develop eccentric control of dynamic
movements
Exercises should be performed technically correct
Core Stabilization Strengthening
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Fundamental component of rehabilitation
Strengthening of core (lumbo-pelvic complex)
Used to
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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
Open vs. Closed Kinetic Chain
Exercises
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Anatomical & functional relationships that exist
in the upper and lower extremity
Open kinetic chain
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May be needed when lower extremity is to be nonweight-bearing
Closed kinetic chain
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Useful in rehabilitation
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Most activities call for weight bearing of foot or hand in some
capacity
May be more functional than open chain activities in some
instances
Training for Muscular Strength vs.
Muscular Endurance
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Strength and endurance are closely related
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For strength development
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As one improves, the tendency is for the other to do
the same
Heavier weight and low repetitions should be used
Endurance training
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Lighter weight and high repetitions (10-15) are
suggested
Resistance Training Differences
Between Males & Females
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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
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Females tend to have a lower ratio due to higher
levels of body fat
Absolute strength differences
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Reduced when body size & composition are compared
Leg strength can actually be stronger in females with
upper extremity strength greater in males
Resistance Training in Young
Athletes
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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
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Pre-pubescent child will experience gains in muscle
strength without muscle hypertrophy
Resistive exercise should be integrated into a
young athlete’s rehabilitation
Close instruction & supervision is necessary
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Base on extent of maturation – critical to effectiveness
Resistance
Training in
Older
Adults
Kisner & Colby, p. 125
Specific Resistive Exercises Used
in Rehabilitation
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Goal of program
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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
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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
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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
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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
References
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Kisner, C. & Colby, L. (2002). Therapeutic
Exercise: Foundations & Techniques, 4th
ed.