Regaining Muscular Regaining Muscular Strength, Endurance Strength, Endurance and Power and Power
Jan 05, 2016
Regaining Muscular Regaining Muscular Strength, Endurance and Strength, Endurance and
PowerPower
Regaining Strength, Endurance & PowerRegaining 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
Types of Skeletal Muscle ContractionTypes 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
Factors That Determine Levels of Factors That Determine Levels of Strength, Endurance & PowerStrength, 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
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
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
Fast-Twitch vs. Slow TwitchFast-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 (a<x<b) Produce quick, forceful contractions Short-term, high intensity activities, ANAEROBIC activities
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
Physiology of Strength DevelopmentPhysiology 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
Other Physiological Adaptations to Other Physiological Adaptations to Resistance ExerciseResistance 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
Techniques of Resistance TrainingTechniques 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 athlete’s response to specific exercise
Be mindful of pain when dealing with progression
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”
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
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
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
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
Resistance Training Techniques Resistance Training Techniques Used in RehabilitationUsed in Rehabilitation
DeLorme’s method 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
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”
Sander’s program Utilized in advanced
stages of rehabilitation Utilizes percentages of
body weight
Knight (DAPRE) Daily Adjustable
Progressive Resistive Exercise
Adjusted based on individual’s progress
Based on 6 RM working weight
Berger 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
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
Isokinetic ExerciseIsokinetic 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
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
1980’s Provide objective means of athlete/patient
evaluation Training at fast vs. slow speeds Functional speeds
Plyometric ExercisePlyometric 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
Core Stabilization Strengthening 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
Open vs. Closed Kinetic Chain Open vs. Closed Kinetic Chain ExercisesExercises
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
Training for Muscular Strength vs. Training for Muscular Strength vs. Muscular EnduranceMuscular 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
Resistance Training Differences Resistance Training Differences Between Males & FemalesBetween 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
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
Resistance Training in Young Resistance Training in Young Athletes 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 athlete’s rehabilitation Close instruction & supervision is necessary
Base on extent of maturation – critical to effectiveness
Resistance Resistance Training in Training in
Older Older AdultsAdults
Kisner & Colby, p. 125
Specific Resistive Exercises Used Specific Resistive Exercises Used in Rehabilitationin 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
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)
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
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
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
ReferencesReferences
Kisner, C. & Colby, L. (2002). Therapeutic Exercise: Foundations & Techniques, 4th ed.