Resistance Exercise for Impaired
Muscle Performance
An introduction
Intro....
 Muscle performance refers to the capacity of a muscle to
do work (force x distance).
 key elements of muscle performance:
 strength
 power
 Endurance
 injury, disease, immobilization, disuse, and inactivity, may
result in impaired muscle performance, leading to
weakness and muscle atrophy
Definition of Resistance exercise
 Any form of active exercise in which dynamic or static
muscle contraction is resisted by an outside force
applied manually or mechanically
 Many factors influence its appropriateness or
effectiveness and how the exercises are designed,
implemented, and progressed
 such as underlying pathology, the extent and severity of
muscle performance impairments, the presence of other
deficits, the stage of tissue healing after injury or surgery,
and a patient’s or client’s age, overall level of fitness, and
the ability to cooperate and learn all must be considered.
Important terms
 Strength
 the ability of contractile tissue to produce tension and a resultant
force based on the demands placed on the muscle.
 the greatest measurable force that can be exerted by a muscle or
muscle group to overcome resistance during a single maximum
effort.
 Functional strength
 the ability of the neuromuscular system to produce or control
forces, during functional activities, in a smooth, coordinated
manner.
Strength training (strengthening exercise)
 It is a systematic procedure of a muscle or muscle group
lifting, lowering, or controlling heavy loads (resistance)
for a relatively low number of repetitions or over a
short period of time.
increase in muscle fiber size.
increase in the maximum force-producing
capacity of muscle
Power
 the work produced by a muscle per unit of time
 In other words  the rate of performing work.
 Power can be enhanced by 2 ways !!
 increasing the work a muscle must perform during a specified
period of time
 reducing the amount of time required to produce a given force.
 The greater the intensity of the exercise and the shorter
the time period taken to generate force, the greater is the
muscle power.
 Plyometric exercises.
Endurance
 The ability to perform low-intensity, repetitive, or sustained activities
over a prolonged period of time
 Cardiopulmonary endurance
 repetitive, dynamic motor activities such as walking, cycling, swimming, or
upper extremity ergometry, which involve use of the large muscles of the
body.
 Muscle endurance - sustained control
 the ability of a muscle to contract repeatedly against a load (resistance),
generate and sustain tension, and resist fatigue over an extended period of
time.
 Maintenance of balance and proper alignment of the body segments
 almost all daily living tasks require some degree of muscle and
cardiopulmonary endurance.
Endurance
 Endurance training:
 characterized by having a muscle contract and lift or lower a
light load for many repetitions or sustain a muscle
contraction for an extended period of time.
 The key elements of endurance training are low-intensity
muscle contractions, a large number of repetitions, and a
prolonged time period.
 Unlike strength training, muscles adapt to endurance
training by increases in their oxidative and metabolic
capacities, which allows better delivery and use of
oxygen.
 For many patients with impaired muscle performance,
endurance training has a more positive impact on
improving function than strength training.
Types of Resistance Exercise
 Manual and Mechanical Resistance Exercise
 Isometric Exercise (Static Exercise)
 Dynamic Exercise—Concentric and Eccentric
 Dynamic Exercise—Constant and Variable Resistance
 Isokinetic Exercise
 Open-Chain and Closed-Chain Exercise
Manual Resistance Exercise
 type of active-resistive exercise in which resistance is
provided by a therapist
 May be applied in a self-resistance form
 in the early stages of an exercise program
 when the range of joint movements needs to be carefully
controlled
 The amount of resistance given is limited only by the
strength of the therapist.
Mechanical Resistance Exercise
 active-resistive exercise in which resistance is applied
through the use of equipment or mechanical
apparatus.
 Resistance can be measured quantitatively and
incrementally progressed over time
 useful when the amount of resistance necessary is
greater than what the therapist can apply manually.
Isometric Exercise (Static Exercise)
 is a static form of exercise in which a muscle contracts
and produces force without an appreciable change in
the length of the muscle and without visible joint
motion.
 Types of Isometric Exercise:
 Muscle-setting exercises
 Stabilization exercises
 Multiple-angle isometrics
Muscle-setting exercises:
 low-intensity isometric contractions performed against
little to no resistance
 used to:
 decrease muscle pain and spasm
 promote relaxation and circulation after injury to soft tissues
during the acute stage of healing
Muscle-setting exercises:
 Effects:
 It does not improve muscle strength except in very weak
muscles
 It can retard muscle atrophy.
 Maintain mobility between muscle fibers when
immobilization of a muscle is necessary to protect healing
tissues during the very early phase of rehabilitation.
Stabilization exercises:
 used to develop a submaximal but sustained level of
co-contraction to improve postural stability or
dynamic stability of a joint
 Encourage mid-range isometric contractions against
resistance in antigravity positions and in weight-bearing
postures if weight bearing is permissible.
Multiple-angle isometrics:
 A system of isometric exercise where resistance is
applied at multiple joint positions within the available
ROM
 used when the goal of exercise is to improve strength
throughout the ROM when joint motion is permissible but
dynamic resistance exercise is painful or inadvisable.
To achieve adaptive changes in static muscle
performance
 an isometric contraction should be held for 6 seconds and
no more than 10 seconds because muscle fatigue develops
rapidly.
 Use of repetitive contractions decreases muscle cramping
and increases the effectiveness.
 To avoid potential injury to the contracting muscle, apply
and release the resistance gradually.
To achieve adaptive changes in static muscle
performance
 beware of Valsalva maneuver that causes a rapid
increase in blood pressure.
 Perform rhythmic breathing, emphasizing exhalation during
the contraction
 High-intensity isometric exercises may be contraindicated
for patients with a history of cardiac or vascular disorders.
Dynamic Exercise—Concentric and Eccentric
Open-Chain and Closed-Chain Exercise
 Open-Chain :
 motions in which the distal segment (hand or foot) is free to
move in space, without necessarily causing simultaneous
motions at adjacent joints.
 Closed-Chain:
 motions in which the body moves on a distal segment that is
fixed or stabilized on a support surface
Open-Chain and Closed-Chain Exercise
 Rationale for Use of Open-Chain and Closed-Chain
Exercises
 Functional activities and exercises are commonly
categorized as having weight-bearing or non-weight-bearing
characteristics.
 High-load, open-chain exercise may have an adverse effect
on unstable, injured, or recently repaired joints, as
demonstrated in the ACL-deficient knee.
Advantages of Resistance Exercise
 Enhanced muscle performance: restoration, improvement
or maintenance of muscle strength, power, and endurance
 Increased strength of connective tissues: tendons,
ligaments, intramuscular connective tissue
 Greater bone mineral density or less bone demineralization
 Decreased stress on joints during physical activity
Advantages of Resistance Exercise
 Reduced risk of soft tissue injury during physical activity
 Improve capacity to repair.
 Improve balance.
 Enhanced physical performance during daily living,
occupational, and recreational activities
Advantages of Resistance Exercise
 Positive changes in body composition: lean muscle
mass or body fat
 Enhanced feeling of physical well-being
 Possible improvement in perception of disability and
quality of life
1. Overload Principle
 If muscle performance is to improve, A load that exceeds the
metabolic capacity of the muscle must be applied; that is, the
muscle must be challenged to perform at A level greater than that
to which it is accustomed.
 If the demands remain constant after the muscle has adapted,
the level of muscle performance can be maintained but not
increased.
Application of the Overload Principle
focuses on the progressive loading of muscle by changing in 2 factors:
 Intensity of resistance.
 Volume(repetition, sets, frequency).
In a strength training program, the amount of resistance applied to the
muscle is incrementally and progressively increased.
For endurance training, more emphasis is placed on increasing the
time a muscle contraction is sustained or the number of repetitions
performed than on increasing resistance.
Precaution
 To ensure safety, the extent and progression of overload must
always be applied in :
 the context of the underlying pathology,
 age of the patient
 stage of tissue healing,
 fatigue
 the overall abilities and goals of the patient.
 The muscle and related body systems must be given time to adapt
to the demands of an increased load or repetitions before the
load or number of repetitions is again increased.
2. Specific adaptation to imposed demands
(SAID Principle)
 The SAID principle helps therapists determine the
exercise prescription and which parameters of
exercise should be selected to create specific training
effects that best meet specific functional needs and
goals.
a. Specificity of Training
 the adaptive effects of training are highly specific to the training
method employed
 exercises incorporated in a program should mimic the
anticipated function
 Consider the mode (type) and velocity of exercise as well as
patient or limb position and the movement pattern during
exercise.
 task-specific practice must always be emphasized
 Ex: ascending and descending stairs.
b. Transfer of Training
 carryover of training effects from one variation of
exercise or task to another
 occur on a very limited basis with respect to the velocity of
training and the type or mode of exercise
c. Reversibility Principle
 Adaptive changes in the body's systems in response to
a resistance exercise program are transient .
 unless training-induced improvements are regularly used for
functional activities
 unless an individual participates in a maintenance
program of resistance exercises.
 Detraining, reflected by a reduction in muscle
performance, begins within a week or two after the
cessation of resistance exercises
Fatigue
 a complex phenomenon that affects muscle performance
and must be considered in a resistance training program.
Muscle (local) fatigue
 This occurs during exercise when a muscle repeatedly contracts
statically or dynamically against an imposed load.
 This acute physiological response to exercise is normal and
reversible.
Muscle (local) fatigue
 Factors leading to decrease muscle strength
 Disturbances in the contractile mechanism of the
muscle itself because of a decrease in energy stores,
insufficient oxygen, and a build-up of H+
 Inhibitory influences from the central nervous system
 Possibly a decrease in the conduction of impulses at
the myoneural junction, particularly in fast-twitch
fibers
Muscle (local) fatigue
 Fiber-type distribution of a muscle reflects how
resistant it is to fatigue
postural muscles:
a heavy distribution
of type I (tonic) fibers
muscles with a large
distribution of type
IIB (phasic) fibers
Cardiopulmonary (general) fatigue
 the diminished response of an individual as the result of
prolonged physical activity.
 related to the body's ability to use oxygen efficiently
 Caused by a combination of the following factors:
 Decrease in blood sugar (glucose) levels
 Decrease in glycogen stores in muscle and liver
 Depletion of potassium, especially in the elderly patient
Factors that influence fatigue
 A patient's health status
 Diet
 Lifestyle (sedentary or active)
 !!! Be familiar with the patterns of fatigue associated with
different diseases and medications.
 multiple sclerosis
 cardiac, peripheral vascular, cancer, and pulmonary diseases
 Environmental factors !!
Recovery from Exercise
Adequate time for recovery from fatiguing exercise
must be built into every resistance training program
intra-session
intersession
 Recovery from acute exercise, where the force-producing
capacity of muscle returns to 90% to 95% of the preexercise capacity, usually takes 3 to 4 minutes
Recovery from Exercise
 Changes that occur in muscle during recovery are:
 Oxygen stores are replenished in muscles.
 Energy stores are replenished.
 Lactic acid is removed from skeletal muscle and blood within
approximately 1 hour after exercise.
 Glycogen is replaced over several days.
Physiological changes due to Resistance Exercise
 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.
a. Neural Adaptations
 Increase in electromyographic (EMG) activity during
the first 4 to 8 weeks of training with little to no
evidence of muscle fiber hypertrophy.
 Also possible that increased neural activity is the
source of additional gains in strength late in a
resistance training program even after muscle
hypertrophy has reached a plateau.
 Motor learning and improved coordination
 Increase recruitment in the number of motor units
firing
b. Skeletal Muscle Adaptations
 Hypertrophy
 increase in the size of an individual muscle fiber
caused by an increase in myofibrillar volume.
 appears within 2 – 8 weeks of resistance exercises
depending on the intensity of these exercises.
 increase in protein (actin and myosin) synthesis.
 associated with biochemical changes that stimulate uptake of
amino acids.
 Greatest with high-volume, moderate-resistance exercise
performed eccentrically.
Skeletal Muscle Adaptations
 Muscle Fiber Type Adaptation
 Type II (phasic) muscle fibers preferentially hypertrophy
 Transformation of type IIB to type IIA is common
endurance training
during the early weeks of heavy resistance training
 This makes the type II fibers more fatigue-resistant.
Skeletal Muscle Adaptations
 Muscle Fiber Type Adaptation
 type I to type II fiber type conversion
denervated limbs of laboratory animals
humans with spinal cord injury
after an extended period of weightlessness associated with space
flight
 little to no evidence of type II to type I conversion under
training conditions in rehabilitation or fitness programs.