Resistance exercises

Definitions:
• Resisted exercise:
Resisted exercise is any form of active
exercise in which dynamic or static muscle
contraction is resisted by an outside force
applied manually or mechanically.

• Strength: Muscle strength is the greatest
measurable force that can be exerted by a
muscle or muscle group to overcome
resistance during a single maximum effort.
• Power: Muscle power is defined as work
produced by the muscle per unit of time.
Power= force X distance/time
• Endurance: It is the ability to perform low
intensity repetitive or sustained activities over
a prolonged period of time.

Types of muscle works:
• Isometric muscle work:
In this type of muscle work there is
increase in tone of the muscle without any
change in the muscle length.
e.g. isometric strengthening for neck
extensors: the clasped hand behind the head
is pushed back by the head. No movement of
the head or neck occurs but the tone of neck
extensors increases.

• Isotonic muscle work: in this type of muscle work
there is change in length of the muscle while it
maintains an even tone throughout the
contraction period. This is of two types:
• Concentric work: here the origin and insertions
come closer and the muscle length shortens.
e.g. getting up from a chair: knee and hip
extensors contract concentrically to bring about
extension in these two joints.
• Eccentric work: here the origin and the insertion
go away from each other and the muscle length
increases.
e.g. sitting on a chair from standing: knee and hip
extensors contract eccentrically to bring about
flexion in these two joints.

• In concentric contraction the force generated
by the muscle is greater than the resistance.
• In isometric contraction force generated by
the muscle is equal to the resistance.
• In eccentric contraction the force generated
by the muscle is lesser than the resistance.

Principles of resistance exercise
Principle of overload:
• If muscle performance is to improve , a load
that exceed the metabolic capacity of the
muscle, must be applied; that is a muscle
must be challenged to perform at a level
greater than to which it is accustomed.
• Overload can be applied by increasing the
intensity or volume. In strength training the
intensity is increased where as in endurance
training the volume i.e. frequency, repetitions
and time is increased.

SAID (Specific Adaptation to Imposed Demand)
principle:
• Adaptations produced by the training are highly
specific to the nature of the stimulus or
overload applied.
• SAID applies to all the systems of the body.
• The adaptations are specific to strength, power,
endurance, functional activity, joint angle,
sequence of muscle activations, energy systems
and virtually all other variable present.

Principle of Reversibility:
• The adaptations achieved through resistance
exercise persist as long as the resistance
exercise is performed regularly and go back
gradually to the pre exercise levels once the
training is stopped. This means the effects of
resistance training are reversible.

Inter individual variability:
• Every individual responds to resistance
exercise in a different way, thus similar stimuli
may bring about a lot of improvement in one
patient and no improvement in others.

Ranges of muscle work
FULL RANGE:
Contraction takes place
throughout the range,
starting from fully stretched
position in case of concentric
contraction and from fully
shortened position in case of
eccentric contraction.
Full range contractions are
normally needed only during
emergencies (e.g. preventing
a fall).
Uses:
Maintain joint mobility
Increase circulation
Preparation for situations when
power & mobility is needed.

INNER RANGE:
The muscle either shortens
concentrically from half way
of its range, or is lengthened
by eccentric contraction
from fully contracted state
to halfway.
Uses:
Gain or maintain joint
movement in the direction
of muscle pull.
Train some extensors that
stabilize joints. E.g. Knee:
VMO strengthening

• OUTER RANGE:
Concentric contraction from
fully stretched position to
halfway range and
eccentric contraction from
halfway range to the fully
contracted position
Uses:
Very useful for initiation of
contraction (stretch reflex
acts better)
Muscles contract more
forcefully (Frank sterling
law)

MIDDLE RANGE:
In this range of muscle work
the muscles neither reach
the fully contracted range
nor are fully stretched, but
moves only in the range
inbetween. This range is
most functional and
generally most efficient
(angle of pull near 90
degree)
USES:
Maintenance of muscle tone
and normal power .

Group action of muscles
1. Prime movers/
agonists
2. Antagonists
3. Synergists
4. Fixators

Indications
1. Curative:
• Muscle: weakness or paralysis
• Bone: to increase density
• Aerobic system: improves aerobic capacity
• Other connective tissues: improve pliability and strength
2. Preventive:
• to preserve muscle power in all the conditions where muscle
weakness is anticipated.
• To live a healthy life with high levels of fitness.
3. Preparative: to prepare for some specific activity where the
adaptations of resistance exercise will be useful, e.g training for arm
muscles of a boxer will prepare him for a better performance.
4. Recreative: various form of resistance training is used as sports and
recreation activity, like body building.

Adaptations of resistance exercise
I. Neural adaptation:
Starts within 4 weeks of regular training.
Caused by decreased CNS inhibition, decreased
GTO sensitivity & changes in NMJ
• Increased number of motor unit recruitment
• Increased rate of firing
• Synchronized firing

II. Skeletal muscle adaptation:
A. HYPERTROPHY
It is increase in the muscle bulk without increase in the
number of muscle fibers, due to increased myofibril
volume.
Starts between 4-8 weeks of resistance training.
Caused by increased protein synthesis and reduced
protein degradation.
Maximum hypertrophy in high volume moderate
resistance exercises performed eccentrically.

B. HYPERPLASIA
It means increase in the no. of muscle fibers.
A small portion of muscle fibers may increase in
number by longitudinal splitting.
C. VASCULAR & METABOLIC ADAPTATIONS
Increased capillary bed density
Increased mitochondrial density
ATP & CP storage increases
Myoglobin storage increases
CPK & Myokinase increases

III. Bone:
Minimizes or prevents loss of bone mineral
density.
Can be used for the treatment of osteoporosis/
osteopenia
IV. Connective tissue
Tensile strength of tendons ligaments and
connective tissue in muscle increases

DETERMINANTS OF RESISTANCE TRAINING
1. Frequency
2. Intensity
3. Time
4. Type
5. Alignment & Stabilization
6. Volume
7. Periodization
8. Rest interval
9. Sequencing
10.Integration to functional activities
The determinants are interdependent for a
successful regime

Repetition maximum
RM is a method of quantifying exercise intensity, Given by
Delorme
Definition:
A repetition maximum is defined as the greatest amount of
weight a muscle can move through the available ROM
for a specific no of times.
1 RM for a muscle is the maximum weight (resistance) with
which the muscle can contract through full/ available
ROM for one time. The muscle will be unable to perform
the repetition for a second time .
10 RM for a muscle is the maximum weight (resistance)
with which the muscle can contract through full/
available ROM for 10 times. The muscle will be unable to
perform the 11th repetition.

Uses of RM
1. To document a baseline measurement of
dynamic strength of a muscle
2. To identify an exercise load to be used
during exercise
3. To find out prognosis in reassessment and
alter the exercise regime accordingly.

How to measure 1RM?
Measured by repetitions to fatigue method
using equations/ charts.
Various equations and charts are available eg.
1 RM=(No of reps/30)+1 X weight used
Example: if one lifts 15 kg for 20 times, 1RM= ?
For reps to fatigue the muscle is warmed up and
stretched and then given a weight (preferably
free weight) which can be performed
comfortably over 5 repetitions. The no. of
repetition the candidate can perform before
fatigue is noted.

Training zone
The amount of resistance to be used in a training
program is usually a percentage of 1 RM
For sedentary: 30-40% of 1 RM
For untrained healthy individual: 60-70% of 1 RM
For highly trained: 80-95% of 1 RM

Time/duration
The duration of a resistance training regime is
the total no. of weeks or months during which
the exercise program is carried out.
Duration determines the adaptations:
< 4 weeks program-neural adaptation only.
6-12 weeks program- musculoskeletal
adaptation
(hypertrophy, increased vascularization)

Alignment and stabilization
Alignment and stabilization is necessary for
isolation of muscle and to prevent
substitution.
Stabilization can be external or internal by
isometric contraction of a fixator, (e.g.
abdominals in case of SLR)

Volume
Volume is the summation of the total no. of
repetitions and sets of a particular exercise
during a single exercise session multiplied by the
resistance used.
Higher the intensity lower the no. of repetitions.
Repetitions
Repetitions is the no. of times a particular
movement is repeated in a series of complete
and continuous excursions against a specific load.
Set
A predetermined no. of repetitions grouped
together is known as a set or bout. After each set
there is a brief interval of rest.

• Determination of repetitions:
It is based on the principle of repetition maximum.
Most commonly 10 repetitions of 10 RM is used. 10
RM is approximately 75% of 1RM.
Alternatively 15 RM (60% of 1 RM) or 5 RM (90% of
1 RM) is used.
A session may have a single set or multiple sets.
Single set exercises are used with low intensity in
early phases of rehab. For strength gaining
multiple sets are recommended.
For strength gain: low repetitions high resistance
For endurance gain: high repetitions low resistance

Types of resistance
• Manual and mechanical
• Static and dynamic
• Concentric and eccentric
• Open and closed chain
• Constant and variable load
• Isokinetic exercise.

PRE
Progressive resistance exercise is a dynamic
resistance training in which a constant external
load is applied to the contracting muscle by some
mechanical means and incrementally increased.
The RM is used as the basis of progression in the
resistance.
Multiple sets are used in a session, which may
consist of 2-3 sets of 6-12 repititions of 6-12 RM
Common variants are DeLorme, Oxford and
McQueen method.

Delorme: 4 sessions weekly, progress 10 RM once weekly
oxford: 5 times weekly

• McQueen Regime:
10reps@ 100% of 10RM
3 sessions weekly. Progress 10 RM every 1-2
week

BRIME
• Gerber & Hicks described a program of brief
isometric exercise of one to six isometric
contractions, held for 3 to 6 secs, with 20 sec
rests between contractions.
• Purpose is to maintain or slightly increase the
strength of quadriceps during acute knee joint
inflammation when the joint is otherwise held
at rest and to avoid increasing blood pressure
when this is a consideration.
• Usually done for arthritis.

Precaution
1. Valsalva
2. Substitution
3. Overwork (weakness)/overtraining (fatigue)
4. Muscle soreness: acute and DOMS
5. Pathological fracture

Contraindication
1. pain:
Pain in free active movement
Acute pain in resisted isometrics
Pain that can not be eliminated by reducing the
resistance
2. inflammation:
Acute inflammation in muscle or inflammatory
neuro muscular pathology
Dynamic exercise is contraindicated in inflammation
of the joint
3. Severe cardiopulmonary disease.
4. Loss of joint integrity

Resistance exercises

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