Assignment for Therapeutic Exercises

8/6/2019 Assignment for Therapeutic Exercises

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Nadeem Shahzad Malik

Roll Number: 26

One Year Additional Course of Physiotherapy

(Batch 2010-2011)

Module:

Therapeutic Exercises 1 (MPG103)

Assignment:Skeletal Muscle Function and Adaptation to Resistance Exercise

King Edward Mediacl University,Lahore


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THE MUSCLE FIBER

The muscular system consists of three Muscle types: Skeletal muscle ((striated or voluntary muscle, which attaches to the skeleton via the tendons)

Cardiac muscle(which composes the heart)

Smooth muscle( non striated or involuntary muscle, which lines the hollow internal organs)

Human skeletal muscleSkeletal muscle is the most abundant tissue in the human body, accounting for 40 to 45% of the total

body weight. The human body has more than 430 skeletal muscles, found in pairs on the right and

left sides of the body. The most vigorous movements are produced by fewer than 80 pairs.

Skeletal muscles have three main functions:

Force generation for movement

Postural support

Heat production during periods of cold stress

StructureSkeletal muscle is made up of bundles of muscle fibers and is surrounded by and held together with connectivetissue.This connective tissue forms three layers, the epimysium which surrounds the whole muscles, the perymysium

which surrounds fascicles or bundles of 10-100 muscle fibers and the endomysium which surrounds individual

muscle fibers. The connective tissue layers hold the muscle together, connect muscle to other structures in the body

and form tendons to connect muscle to bone.When a muscle contracts, tension is transmitted through the

connective tissue which pulls on the muscle insertion and produces movement.

ContractionMuscles contract according to sliding filament theory.

Nerve supplyMotor neurons stimulate muscles to contract.

Each motor neuron supplies group of motor fibers within a muscle this is called motor unit.

Blood SupplyMuscles are well supplied with blood vessels.There are many capillaries in the endomysium to deliver oxygen &

other nutrients and to remove waste products..


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Skeletal muscle fiber typesSkeletal muscles are composed of various types of muscle fibers and based on metabolic and contractile characteristics are

classified into two groups:

Type 1Type 1 (tonic, slow-twitch) muscle fibers generate a low level of muscle tension but can sustain the contraction

for a long time.

These fibers are geared toward aerobic metabolism.

Type 1 fibers are more resistant to fatigue than type 2A.

Type 1 fibers contain a large number of mitochondria and myoglobin and a high concentration of mitochondrial

enzymes.

This type of fiber has low myosin ATPase activity and slow calcium handling ability and shortening speed and

hence generates comparatively less force.

Type 1 fibers generate energy for ATP resynthesis mainly via oxidative phosphorylation.

Thus, this type of fiber is predominately utilized during prolonged aerobic exercise since it is relatively fatigue

resistant because of lower force generation and also has an abundant supply of energy via oxidative

phosphorylation.

A heavy distribution of type 1 (tonic) fibers is found in postural muscles, which allows muscles such as the soleus

to sustain a low level of tension for extended periods of time to hold the body erect against gravity or stabilize

against repetitive loads.

Type 2

Fifty percent of type2 muscle fibers are 2A & fifty percent are 2B.

In contrast to type 1, type 2 or fast-twitch fibers possess a high capability for electrochemical transmission ofaction potentials and increased activity of myosin ATPase, and hence larger force generation.

Calcium is also rapidly released by the sarcoplasmic reticulum, which contributes to this fibers rapid ATP

turnover for short, intense periods of muscular contraction.

Type 2 fibers rely heavily on the glycolytic system for energy production; thus this fiber type is particularly suited

to exercise of an anaerobic nature and correspondingly these fiber types also tend to fatigue more rapidly than

type 1 fibers.

In general type 2 fibers generate a great amount of tension within a short period of time, with type 2B being

geared toward anaerobic metabolic activity and having a tendency to fatigue more quickly than type 2A fibers.

Muscles with a large distribution of type 2B (phasic) fibers, such as the gastrocnemius or biceps brachii, produce

a great burst of tension to enable a person to lift the entire body weight or to lift, lower, push, or pull a heavy

load but fatigue quickly.

Characteristics of Human Skeletal MusclesCharacteristics Type1

Fibers

Type 2A

Fibers

Type 2B

Fibers

Diameter Small Intermediate Large

Motor neuron size Small Large Large

Resistance to fatigue High Intermediate Low

Capillary density High High Low

Energy system Aerobic Aerobic Anaerobic

Twitch rate Slow Intermediate Fast

Maximum muscle-

shortening velocity

Slow Fast Fast

Nerve conduction Slow Fast Fast

Contractile speed Slow Fast Fast

Fatigue Resistance High Moderate Low

Motor unit strength Low High High

Oxidative capacity High Moderate Low

Glycolytic capacity Dense Dense Sparse

Myoglobin content High Intermediate Low


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RESISTED EXERCISES

Any form of active exercise in which a dynamic muscular contraction is resisted by an outside force.A. Manual resistance exercise, a type of active exercise in which a dynamic or static muscular contraction is resisted

by an outside force.

B. Mechanical resistance exercise, resistance is applied through the use of equipment or mechanical apparatus.

Goals of Resistance Exercise:A. Increase strength (primarily achieved through increased loads and intensity)

B. Increase muscular endurance (primarily achieved through low-intensity repetitive exercise over a prolonged

period of time)

C. Increase power (primarily achieved through increased velocity and speed Of exercise)

Effects of Resistance Exercise:

Resistance exercises are essential elements of rehabilitation programmes for persons with impaired function.These exercises

Help in promotion & maintenance of health & well being.

Enhance performance of motor skills.

Prevent or reduce risk of injury.

In applying resistance to muscles four rulesmust be observed:1. It must be given smoothly from the beginning to the end of the movement.

2. Whenever possible it should be applied to the moving part so that it exerts pressure on the surface of the

skin facing the direction of the movement. In this way the exteroceptors are stimulated and movement

is facilitated.

3. It should diminish gradually from the beginning to the end of the movement, so as to conform to

the physiological principle that muscles are capable of exerting their greatest force when they are

fully extended, and that as they shorten their force diminishes.

4. A brief period of complete relaxation should follow each muscular effort.


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SKELETAL MUSCLE FUNCTION

Skeletal muscles are used for a wide variety of motor tasks ranging from maintaining posture to whistling,

from jumping to breathing, from running at 40Km/h for 10s (100 meters) to running at half the speed for 2h

(i.e., the marathon, 42,195Km).

The capacity to accomplish such variable motor tasks relies on the very fine motor control performed by the

nervous system and on the very large functional heterogeneity and plasticity of skeletal muscles.

Types of Muscle Contraction

Type Speed Resistance Joint MotionIsometric Fixed Fixed (0 degrees/sec) NO

Isotonic Variable Fixed YES

Isokinetic Fixed Variable(accommodating) NO

Muscles assume different roles during joint motion, depending on such variables as the motion being performed,

the direction of the motion, and the amount of resistance the muscle must overcome. If any of these variables

change, the muscles role may also change.

Knowledge of the factors that influence the force producing capacity of normal muscle during an active

contraction is fundamental to understand how the neuromuscular system adapts as the result of resistance

training.This knowledge provides a basis on which a therapist is able to make sound clinical decisions when

designing a resistance exercise program for patients with weakness and functional limitations as the result of

injury or disease or to enhance physical performance and prevent or reduce the risk of injury in healthy individuals.


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Factors that Influence Tension Generation in Normal Skeletal Muscle

Muscle Performance

Its a capacity of muscle to do work (force x distance).

A complex component of functional movement.

Diverse but interrelated factors affect the tension generating capacity of normalskeletal muscle necessary

to control the body and perform motor tasks.

Key Elements of Muscle PerformanceSTRENGTH

The ability of contractile tissue to produce tension and a resultant force based on the demands placed upon the

muscles.

The greatest measureable force that can be exerted a muscle group to overcome resistance during a single

maximum effort.

Strengthening Exercises are systemic procedure of a muscle or muscle group lifting, lowering or controlling heavyloads (resistance) for a relative low number of repetitions or over a short period of time.

Most common adaptation to heavy resistance training: increase in maximum force producing capacity of muscle

(increase in muscle strength) due to neural adaptations & increase in muscle fiber size.

POWER

Related to strength & speed of movement.

Work(force x distance) produce by muscle per unit of time (force x distance/time)

Rate of performing work

Can be expressed by single burst of high intensity activity (anaerobic power) or by repeated burst of less intense

muscle activity (aerobic power).

ENDURANCE

The ability to perform low intensity, repetitive or sustained activities over a prolonged period of time.

Cardio respiratory Endurance (Total body endurance) is associated with repetitive dynamic motor activities that

involve the use of large muscles of body.

Muscle Endurance (Local Endurance) is a ability of muscles to contract repeatedly against a load (resistance),

generate and sustain tension and resist fatigue over an extended period of time.

Endurance Exercises are having a muscle contract and lift or lower a light load for many repetitions or sustain amuscle contraction for an extended period of time.

Endurance training will have a more positive impact on improving function than strength training in patients with

impaired muscle performance.

Minimize adverse forces on joints, produce less irritation on tissues and is more comfortable for patients than

heavy resistance training.


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Factors that may affect muscle PerformanceMorphological qualities of muscles

Biomechanical influences

Neurological

Cardio vascular

RespiratoryEmotional

Metabolic & Biochemical

Age

Psychological and cognitive factors

Morphological qualities of muscles: Cross-section and size of the muscle (includes muscle fiber number& size)

Influence:The larger the muscle diameter, the greater its tension producing capacity

Fiber arrangement & fiber length

Influence:Short fibers with pinnate and multipinnate design in high force producing muscles (ex. quadriceps,

gastrocnemius, deltoid, biceps brachii)

Long parallel design in muscles with high rate of shortening but less f orce production (ex. sartorius,

lumbricals)

Biomechanical influences: Fiber-type distribution of muscle: type I (tonic, slow twitch) and type 2A & 2B ( phasic, fast-twitch)

Influence: High percentage of type I fibers: low force production, slow rate of maximum force development,

resistant to fatigue

High percentage of type 2A a nd 2B fibers: rapid high force production; rapid fatigue

Length-tension relationship of muscle at time of contraction

Influence: Muscle produces greatest tension when it is near or at the physiological resting position at the time

of contraction

Type of muscle contraction

Influence: Force output from greatest to least: eccentric, isometric, concentric muscle contraction

Speed of muscle contraction(force velocity relationship)

Influence: Concentric contraction: speed tension. Eccentric contracon: speed tension

Neurological Factors: Recruitment of motor units

Influence: Great number of motor units required great tension

Frequency of firing of motor units

Influence: Higher the frequency higher the tension produced

Metabolic & Biochemical Factors: Energy stores & blood supply

Muscle needs adequate sources of energy (fuel) to contract, generate tension and resist fatigue.

There are three main energy systems (ATP-PC system, anaerobic/glycolytic/ lactic acid system, aerobic system)

Fatigue(Local)

Its a diminished response of a muscle to repeated stimulus. Fatigue is reflected by progressive decrement in

amplitude of motor unit potentials. This occurs during exercise when a muscle repeatedly contracts statically or

dynamically against an Imposed load. Decline in force producing capacity of neuromuscular system may be

considered normal or reversible, it could be due to

Decrease in energy stores ,insufficient oxygen or lactic acid build up

CNS inhibition

Decrease conduction in NMJ (Particularly type 2 fibers)


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Signs and Symptoms of Muscle Fatigue Muscle pain

Active movements jerky not smooth

Inability to complete full range of available motion during dynamic exercise against the same level of resistance Use of substitute or incorrect motions to complete the movement pattern

Inability to continue low-intensity physical activity

When these signs and symptoms develop during resistance exercise, it is time to decrease the load on the

exercising muscle or stop the exercise and shift to another muscle group to allow time for the fatigued muscle to

rest and recover.

Cardiopulmonary Fatigue (General)Its a diminished response of a i ndividual due to prolonged physical activity. This fatigue is related to efficient

oxygen usage of body.

Could be due to

Decreased blood glucose level(hypoglycemia)

Decreased glycogen stores in muscle & liver

Depletion of potassium (specially in elderly)

THRESHOLD FOR FATIGUE

Level of exercise that cannot be sustained indefinitely.

Could be noted as

Length of time contraction is maintained

Number of repetitions of exercise that can initially be performed

Factors that influence fatigue Health status

Diet

Life style(sedentary or active)

Presence of disease

Environmental factors such as outside or room t emperature, air quality, and altitude, also influence how quickly

the onset of fatigue occurs and how much time is required for recovery from exercise

Recovery from exerciseRecovery from exercise usually takes 3 to 4 minutes.

Changes that occur in muscle during recovery are:

Energy stores are replenished

Lactic acid is removed approximately 1 hour after exercise

Oxygen stores are replenished

Glycogen is replaced over several days

If light exercise is performed during the recovery period (active recovery), recovery from exercise occurs more

rapidly than with total rest (passive recovery).

Faster recovery with light exercise is probably the result of neural as well as circulatory influences.


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Age:Muscle performance changes throughout the life span.

Muscles develop for both sexes equally during early stages of life.

Muscles continue to develop until adulthood with the men gaining more muscle mass & strength than women.

Women reach their peak muscle strength faster than men.

Muscles development declines faster as we pass late adulthood.

Age-Related Changes in Muscle and Muscle Performance

Infancy, Early Childhood, and Preadolescence At birth, muscle accounts for about 25% of body weight.

Total number of muscle fibers is established during infancy.

Postnatal changes in distribution of type 1 and type 2 fibers in muscle are relatively complete by the end of the

first year of life.

Muscle fiber size and muscle mass increase linearly from infancy to puberty .

Muscle strength and muscle endurance increase with chronological age in boys and girls throughout childhood

until puberty.

Muscle mass and muscle strength is slightly greater (approximately 10%) in boys than girls from early childhood

to puberty.

Puberty During puberty muscle mass increases more than 30% per year.

Rapid increase in muscle strength in both sexes.

Marked difference in strength levels develops in boys and girls.

In boys, muscle mass and body height and weight peak before muscle strength; in girls, strength peaks before

body weight.

Young and Middle Adulthood Muscle mass peaks in women between 16 and 20 years of age; muscle mass in men peaks between 18 and 25

years of age.

Decreases in muscle mass occur as early as 25 years of age.

Muscle mass constitutes approximately 40% of total body weight during early adulthood, with men having

slightly more muscle mass than women.

Strength continues to develop into the second decade especially in men.

Muscle strength and endurance reach a peak during the second decade, earlier for women than men.

By sometime in the third decade, strength declines between 8% and 10% per decade through the fifth or sixthdecade.

Strength and muscle endurance deteriorate less ra pidly in physically active versus sedentary adults.

Improvements in strength and endurance are possible with only a modest increase in physical activity.

Late Adulthood Rate of decline of muscle strength accelerates to 15% to 20% per decade during the sixth and seventh decades

and increases to 30% per decade thereafter.

Loss of muscle mass continues; by the eighth decade, skeletal muscle mass has decreased by 50%.

Atrophy of type 2 muscle fibers.

Decrease in the speed of muscle contractions and peak power.

Gradual decrease in endurance and maximum oxygen uptake.

Loss of flexibility reduces the force-producing capacity of muscle.

Minimal decline in performance of functional skills during the si xth decade.

Significant deterioration in functional abilities by the eighth decade associated with a decline in muscular

endurance.

The ability to sustain low-intensity muscular effort also declines in late adulthood because of reduced blood

supply and capillary density in muscle, decreased mitochondrial density, changes in enzymatic activity level, and

decreased glucose transport. As a result, muscle fatigue may tend to occur more readily in the elderly

With a resistance training program, a significant improvement in muscle strength, power, and endurance is

possible during late adulthood.


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Psychological and Cognitive Factors:

Psychological factors can positively or negatively influence muscle performance. For example, fear of pain, injuryor re injury ,depression related to physical illness, or impaired attention or memory as the result of age, head

injury, or the side effects of medication can adversely affect the ability to develop or sustain sufficient muscle

tension.

Psychological factors can also positively influence physical performance.

Attention: Patient may be able to focus on given task.Attention involves the ability to process relevant data

while screening out irrelevantinformation from the environment and to respond to internal cues from the body.

Both are necessary when first learning an exercise and later when carrying out an exercise program

independently.

Motivation: Patient must be willing to put sufficient effort and adhere to an exercise program over time to

improve muscle performance for functional activities. Use of activities that are meaningful and periodically

modifying an exercise routine help maintain a patients interest in resistance training. Charting or graphing a

patients strength gains also helps sustain motivation.

Feedback: feedback can have a positive impact on a patients motivation and subsequent adherence to anexercise programe.For Example, some computerized equipment, such as isokinetic dynamometers, provide visual

or auditory signals that let the patient know if each muscle contraction during a particular exercise is in a zone

that causes a training effect.Documenting improvements over time, such as the amount of weight (exercise load) used during various

exercises or changes in walking distance or speed, also provides positive feedback to s ustain a patients

motivation in a resistance exercise program.


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SKELETAL MUSCLE ADAPTATION TO RESISTANCE EXERCISES

Physiological Adaptations to Resistance ExerciseThe use of resistance exercise in rehabilitation programs has a substantial effect on all systems of the body. Resistance

exercises are equally important for patients with impaired muscle performance and for those who wish to improve or

maintain their level of fitness or reduce the risk of injury. When body systems are exposed to a greater than usual but

appropriate level of resistance in an exercise program, they initially react with a number of acute physiological responses

and then later adapt. That is, body systems accommodate over time to the newly imposed physical demands.

Training-induced adaptations to resistance exercise are known as chronic physiological responses.

Adaptations to overload create changes in muscle performance, its determines the effectiveness of a resistance training

program. The time course for these adaptations to occur varies from one individual to another and is dependent on a

persons health status and previous level of participation in a resistance exercise program.

An adaptation to exercise training demonstrates a diverse range of integrative approaches from the peripheral to the

molecular level. The adaptations can be divided majorly into those that occur in the nervous system and those that occur

directly within muscle tissue.

Neural Adaptations: The ability of the muscles to produce force is first initiated in the nervous system not adaptive changes in muscle

itself.This is reflected by an increase in electromyographic (EMG) activity during the first 4 to 8 weeks of training

with little to no evidence of muscle fiber hypertrophy.

Neural adaptations are attributed to motor learning and improved coordination.

The neurologic factors that modulate muscle induced force production are motor unit recruitment & rate of

motor unit firing.These two factors together are called c entral activation.

It is assumed that these changes are caused by a decrease in the central nervous system (CNS) inhibition,

decreased sensitivity of the Golgi tendon organ (GTO), or changes at the myoneural junction of the motor unit.

Skeletal Muscle Adaptations: Muscle size changes with age

Cross-sectional studies suggest that muscle mass declines at the rate of 0.51.0% per year after the age of 40

years.

Hypertrophy

Hypertrophy is an increase in the size (bulk) of an individual musclefiber caused by an increase in myofibrillar

volume occurs after 4-8 weeks of regular resistance training.Or it may occurs possibly 2-3 weeks with high intensity resistance training due to

Increase in protein synthesis & decrease in protein degradation.

Stimulate uptake of amino acids.

The greatest increases in protein synthesis and therefore hypertrophy are associated with high-volume,

moderate resistance exercise performed eccentrically. In addition, it is the type 2B muscle fibers that appears to

increase in size with resistance training.

There is minimal or no change with endurance training.

Hyperplasia

Hyperplasia is Increase in number of muscle fibres.

It occurs due to longitudinal splitting of muscle fibres.

It is assumed that fiber s plitting occurs when individual muscle fibers increase in size to a point where they are

inefficient, then subsequently split to form two distinct fibers.

The general opinion is that hyperplasia either does not occur or to a slight degree, its impact is i nsignificant.

It accounts for a very small proportion (less than 5%) of the increase in muscle size that occurs with resistance

training.

Muscle Fiber Type Adaptation

Type 2 muscle fibers preferentially hypertrophy with heavy resistance training.

Type 2B become type 2A(common with endurance training & during the early weeks of heavy resistance

training). It makes the muscle more fatigue resistant. However there is little to no evidence of type 2 to type 1

conversion under training conditions in rehabilitation or fitness programs.


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Adaptations of Connective TissuesTensile strength of tendons, ligaments, connective tissues of muscle as well as bone increase with resistance

training designed to improve the strength or power of muscles. Tendons, Ligaments, and Connective Tissue in Muscle

Strength improvement in tendons occurs at the musculo-tendinous junction.

Increased ligament strength may occur at the ligamentbone interface.

It is believed that tendon and ligament tensile strength increases in response to resistance training to support the

adaptive strength and size changes in muscle.

The connective tissue in muscle (around muscle fibers) also thickens, giving more support to the enlarged fibers.

Consequently, strong ligaments and tendons may be less prone to injury.

Non contractile soft tissue strength may develop more rapidly with eccentric resistance training than with other

types of resistance exercises.

Bone

There is increase in bone mineral density with no change or possible increase in bone mass.

Physical activities and exercises particularly those performed in weight-bearing positions are typically

recommended to minimize or prevent age-related bone loss. They are also prescribed to reduce the risk of

fractures or improve bone density when osteopenia or osteoporosis is already present.

Resistance exercises performed with adequate intensity and with site-specific loading through weight bearing ofthe bony area has been shown to increase or maintain bone mineral density.

In contrast a number of studies in young, healthy women and postmenopausal women have reported that there

was no significant increase in bone mineral density with resistance training.

The intensity of the weight training programs may not have been high enough to have an impact on bone

density. It may take as long as 9 months to a year of exercise for detectable and significant increases in bone

mass to occur.

Vascular Adaptations: With endurance training, when muscles hypertrophy with high-intensity, low-volume training the capillary bed

density decreases because of an increase in the number of myofilaments per fiber.

Athletes who participate in heavy resistance training have fewer capillaries per muscle fiber than endurance

athletes and even untrained individuals.

Metabolic Adaptations: Decrease in mitochondrial density occurs with high-intensity resistance training.

This is associated with reduced oxidative capacity of muscle.

Increase in ATP & CP storage.

Increase myoglobin storage.

Increase triglyceride storage (endurance training).


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R E F E R E N C E S

1.The Physiotherapist Pocket Guide To ExerciseBY Angela Glynn PhD, MCSP & Helen FiddlerMSc PG Cert.Introduction to Exercise Physiology. Page 1-3

2. PROGRESSIVE EXERCISE THERAPY IN REHABILITATION AND PHYS ICAL EDUCATION

BY John H. C. Colson FCSP FSRG & Frank W. Collison MSRG 4thEdition .SPECIFIC EXERCISE THERAPY page 21

3. EXERCISE THERAPY P revention and treatment of disease

BY John Gormley and Juliette Hussey.Exercise and the musculoskeletal system,Page 37-47

4.Role of Physical Exercise in Prev enting Disease and Improving the Quality of Life

BYVilberto Stocchi ,Pierpaolo De Feo & David A.Hood. Cellular and Molecular Mechanisms of Skeletal Muscle

Plasticity.Page 4

5. Clinical Kinesiology andAnatomyBY Lynn S. Lippert, MS, PT 4

THEdition.Muscular System.Page 35-39

6.Adaptations to Aerobic and Resistance Exercise in the ElderlyBY Charles P. Lambert and William J. Evans.Reviews in Endocrine & Metabolic Disorders 2005-6 Page.137143

7. Therapeutic Exercise Foundations and Techniques

BYCAROLYN KISNER, PT, MS & LYNN ALLEN COLBY, PT, MS 5TH

Edition. Resistance Exercise For Impaired Muscle

Performance. Page 151-159

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Assignment for Therapeutic Exercises