RESISTANCE EXERCISE
RESISTANCE EXERCISE
• Definition
• Resistance exercise is active exercise
(a dynamic or static muscular contraction)
in which muscle contraction is resisted by
an outside force. This outside force may
be manual or mechanical.
Goals and indications of resistive
exercises
A.
Increase muscle strength
Strength refers to the force out put of a contracting muscle and is
directly related to the amount of tension of contracting muscle.
In order to increase the strength of a muscle, the muscle must be
loaded or resisted so that the increasing level of tension will
develop due to hypertrophy and recruitment of muscle fibers.
B. Increase muscular endurance:
Endurance is the ability of the muscle to perform low intensity
repepitative exercises over a prolonged period of time
Muscular endurance is improved by performing exercises against
mild resistance for many repetitions.
• Increase power
• Power is defined as work per unit of time (Force x distance/time)
• The rate at which a muscle contracts and develop force throughout
the range of motion and relationship of speed and force are factors
that affect power.
• There is no question that strength, endurance and power are all
related and can be improved with resistance exercises.
Physiological Adaptations to Resistive
Exercise
• Regular resistive exercise is associated
with several positive adaptations which is
dosage dependant. These changes
include:
• Muscle
• Increase of the cross sectional area of the
muscle due to
– increase myofibril per muscle fiber
– fibers splitting
– increase number of muscle fiber
• Increase protein content of the muscle fiber.
• Increase energy source necessary to fuel
muscle contraction and increase levels of ATP,
and creatine phosphate.
• Increase neural activation, motor unit
recruitment, and firing rate of each unit.
• Connective tissue
• Resistive exercise may alter tendon and ligament
structure make them larger stronger and more resistance
to injury.
• Increase tensile strength of tendon and ligament
• Bone
• Improve and maintain bone density.
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Cardiovascular system
Increase cardiac output
Increase stroke volume
Increase maximal oxygen consumption
Decrease heart rate
Decreased or unchanged systolic and diastolic blood
pressure.
Overload Principle:
• the foundation of training to increase
muscular strength and endurance is the
overload principle which states that “In
order to increase strength or endurance a
load that exceeds the metabolic capacity
of the muscle must be used to induce
adaptive changes in muscle that lead to
increasing strength and endurance”
Resistance Exercise
Isometric
Isokinetic
Isotonic
Isometric Resisted Exercise
• Isometric resisted exercise is a static contraction of
muscle against external resistance without appreciable
change in its length or joint motion.
• Advantage
• Isometric exercise is valuable when joint motion is
uncomfortable or contraindicated, during immobilization.
• Isometric exercise is effective when weakness exist at a
specific point in the ROM.
• Easy to understand.
• Disadvantage
• Isometric strength is specific to the joint angle (joint
angle dependent).
Isotonic Resisted Exercise
• Isotonic resisted exercise is dynamic exercise that is
carried out against resistance as a muscle lengthens or
shortens through the available range of motion.
• CONCENTRIC CONTRACTION occurs when active
muscle undergoes shortening while overcoming external
resistance.
• ECCENTRIC CONTRACTION occurs when active
muscle undergoes lengthening while being overcome by
an external resistance.
• Eccentric contraction performed against supramaximal
resistance generates greater force production than
concentric contraction.
Mode of Resistance Application
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Manual Resisted Exercise
Manual resistance exercise is active resisted exercise in which the
resistance force is applied by the therapist to either a dynamic or isometric
contraction.
Advantage
The resistance can be varied with changes in strength production
throughout the range.
When joint motion is allowed, manual resisted exercise offer an easy
inexpensive method of strengthening muscle.
Specific or individual muscle could be strengthened.
Disadvantage
The amount of resistance depend on the therapist condition.
The resistance can not be measures so the treatment results can not be
documented.
Effort and time consuming as the therapist can treat only one patient at a
time.
Mechanical Resistance Exercise
• Mechanical Resistance Exercise
• Mechanical resisted exercise is active resisted exercise
in which the resistance provided by equipments to either
a isotonic or isometric muscle contraction.
– A variety of mechanical equipment are available ranging from
simple to complex, small to large, and expensive to inexpensive.
The choice between them depend on the patients need and
ability, goal of the exercise and availability of the apparatus.
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Free weights
Weight machine
Exercise bicycle
Pulley system
• Advantage
• Objective quantitative documentation of the
patient progress.
• The level of resistance not limited by the
therapist strength.
• Add a variety to the exercise.
• Safe time and effort of the therapist.
• Disadvantage
• The resistance can not be varied throughout the
range of motion. Amount of resistance is fixed all
over the range.
• Need space and may be expensive.
Exercise Dose
Position
Lever arm
Repetitionٌٌ
Duration
Amount
Speed
The exercise dosage can be increases
by:
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1- Changing the relationship to gravity
2- Increase lever arm (hand placement)
3- Increase repetition of exercise
4- Increase duration of exercise
5- Increase amount of resistance (mild- moderatemaximum)
• 6- Speed
• Be sure not to proceed to a more difficult exercise before
the patient perform the lower graduation first, otherwise
overwork and fatigue occur
Isokinetic Resistive Exercise
• Isokinetic exercise is a form of active exercise in which a
muscle or group of muscles contracts against a
controlled accommodating resistance which is moving at
a constant angular velocity.
• The isokinetic exercise are performed with a specialized
apparatus that provides variable resistance to a
movement, so that no matter how much effort is exerted,
the movement takes place at a constant speed.
– The isokinetic device are computerized training and testing
device that provide maximum resistance through the entire
ROM.
– The device provide multi-angle isometric resistance, resisted
concentric and eccentric exercise.
Advantage
• Ability to fully activate more muscle fiber for
longer period because the machine
accommodate the resistance according to the
changing ability throughout the ROM.
• Allow training at a variety of speeds
• Provide objective documentation
• The isokinetic device provides many
strengthening protocols to chose from according
to the patient condition and the goal of exercise.
For example (isometric conditioning, isokinetic
conditioning, eccentric & eccentric conditioning
and open & closed chain conditioning)
Disadvantage
• The device is expensive
• Require trained personnel for setting up
the patient training program.
Precaution with Resisted Exercise
• The use of valvasia maneuver should be
avoided during resistive training especially by a
patient with cardiopulmonary disease, recent
abdominal, intervertebral disc, or eye surgery.
• During resistive training especially with eccentric
contraction and increase exercise dose minor
lesions of the muscle and inflammation occur
resulting in delayed onset muscle soreness. If
this occur, start with warming up period and
decrease exercise dose.
Contraindication of Resisted Exercise
• Acute inflammation of the musculoskeletal
system
• Pain
• Infection.
• Recent fracture or non-united fracture