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.