Arshish is the author

1. MUSCULAR CONTRACTIONS
AND MOVEMENT

2. TYPES OF
CONTRACTIONS
There are three main types of muscular
contractions: -
 Concentric - shortening
 Eccentric - lengthening
 Static - isotonic and isometric
1. Concentric/shortening contraction
The Ms shortens. One end stabilizes and
the other pulls the attachment close to the
other. The joint is a fulcrum/pivot.
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3. TYPES OF
CONTRACTIONS
2. Eccentric /lengthening contraction
Gradual release of a contraction e.g –
when one lowers a weight slowly
The muscle returns to its normal length.
3. Static contraction
The muscle remains in partial or complete
contraction two kinds
Isotonic and Isometric contraction
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4. TYPES OF
CONTRACTIONS
a) Isotonic - (equal tension)
Contraction where tension remains
constant as the muscle shortens the
antagonist contracts with equal tension
thus balancing/counter balancing each
other.
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5. TYPES OF
CONTRACTIONS
b) Isometric - (equal length)
Contraction without any appreciable change
in length. The muscle is unable to shorten
due to the magnitude of resistance. Muscle
remains in either partial or maximum
contraction against a force e.g gravity.
e.g.
 Pushing against a wall,
 Holding a book with an outstretched arm,
 Tag of war between equally matched opponents.
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6. GROSS BODY MOVEMENT
There are different types of motion that
the body undergoes.
This is as result of the collaborative
effort of muscles and joint action
controlled by the nervous system.

7. GROSS BODY MOVEMENT
a) Sustained force movement - (SF)
 Force applied against a resistance by
contracting mover muscle – (agonist)
while the antagonists are relaxed e.g.
lifting a heavy load (SF +)
 The weight is lowered the resistance
overcomes the force of the agoutis as
they contract eccentrically (SF -)
 Holding a weight stationary requires that
the sustaining force be equal to the
resistance (SFO)

8. GROSS BODY MOVEMENT
b) Passive Movement (PAS)
Any boy movement that takes place
without continuing muscle contraction
There’re 3 subdivisions
(i) Manipulation (MAN)
Motive force is another person rather
than gravity or muscle force e.g. – being
lifted up
Ballet dancing /skating
movement on a patient by a therapist.

9. GROSS BODY MOVEMENT
(ii) Inertial movement – (INER)
Coasting
 Continuation of movement from a
previously established momentum; it
includes influence from friction, air
resistance tissue viscosity, residual
tension in ligaments etc.
 e.g. - glide phase in breaststroke
swimming – horizontal component of
long jump

10. GROSS BODY MOVEMENT
(iii) Gravitational movement (GRAV)-
‘Falling’
Results from acceleratory force that is
constant in direction and magnitude e.g
– related pendulum movement of limbs
as in dancing
◦ Gymnastics
◦ Free fall

11. GROSS BODY MOVEMENT
 Ballastic Movement (BAL)
A compound movement of 3 phases: -
 Phase I: SF + - body parts accelerated by
concentric contraction of agonists
 Phase II: Inertial /coasting – without muscular
contraction
 Phase III: Decceleration resulting from eccentric
contraction of antagonist SF- and passive
resistance by ligaments and stretched muscles.
The three stages overlap

12. Ballastic Movement
Examples: -
 Batting a baseball
 Smashing a badminton bird
 Spiking in volleyball
 Stroking a tennis ball
 More????????

13. GROSS BODY MOVEMENT
 Guided movement (Gut)/Tracking
When great accuracy and steadiness but
not force or speed are required, both the
agonist and antagonists are active
When errors appear as alternate
domination of antagonistc pair –Tremor
occurs. In absence of these errors
steadiness results.
Steadiness may be required in guided
movements as well as stationary holding.

14. Guided Movements
Examples:
 Writing
 Threading a needle
 Watch repairing
 Lifting a cupful of coffee
 Dart throwing.
 More??????

15. GROSS BODY MOVEMENT
 Dynamic Balance Movement (DB)
Muscle spindles detect deviations from a
desired position of balance and imitate a
servo-control system to make corrections.
The result is a series of irregular
oscillations, precisely medicated by reflex
contraction of appropriate muscle groups
to maintain the balanced position
 e.g erect standing

16. GROSS BODY MOVEMENT
 Oscillating movement (OSC)
 The movement is repidly reversed at the
end of each short excursion, with co-
contracting antagonist muscle groups
alternating dominance.
e.g –
Shaking
Weight
Inertia
Strength of muscles

17. Oscillating movement (OSC)
Established Maximum rhythms for the
Upper extremity:
 Shoulder - 5-6 movement per sec.
 Elbow - 8-9 movements per sec
 Wrist -10-11 movement per
sec
 Fingers - 8-9 movement per
sec.
Flexions are faster than extensions

18. PHYSIOLOGY OF MUSCULAR
CONTRACTION
Revise the following
 Propagation of impulses (Saltatory
Conduction)
 Depolarization – effects of Na+ and
K+
 Neuro muscular Transmission:

19. MECHANICS OF MUSCULAR
CONTRACTION
These are physical rearrangement
which take place during muscle
contraction.
1. Twitch:
This is spasmodic contraction of a
muscle following stimuli
(Diag)

20. 2. Treppe:
Where complete single twitches rapidly
follow each other. The first few
contraction progressively increase in
height
This is treppe – or “ staircase effect”
(Diag)

21. 3. Wave Summation
Where a second stimulus is received
while the muscle is still contracted. This
increases the shortening and tension. The
final force exerted may be 4 times as
great as that afforded by a series of single
twitches.

22. 4. Tetanus:
If successive stimuli are administered
very rapidly no time is allowed for the
muscle to relax. This fusion of
superimposed twitches is known as
tetanus or tetanic contraction. This is the
normal type of voluntary muscular
contraction and may be maintained until
fatigue interview - Tetanic contraction in
voluntary muscle is maintained by a
series of nerve impulses ranging from 5-
50 or more per second in each nerve fiber

23. All or None
 The magnitude of the response is
independent of the magnitude of the
stimulus provided that the stimulus
achieves at least a certain threshold
value
 This depends upon factors like
temperature, chemical state, elapsed
time from previous stimulus etc.

24. Gradation of contraction
The strength of contraction (gradation)
results from the interaction of 3 factors –
i. Recruitment; the number of motor
units stimulated
ii. Summation; the frequency of stimuli
iii. Synchronization; the timing of stimuli
to various motor units
When a sudden great effort is required -
impulses to many or all motor units occur
simultaneously.

25. Rhythmic and arrhythmic
contractions
a) Fibrillation:- Rapid, uncoordinated
rhythmical twitching of individual muscle
fibres that accompanies atrophy of
muscle following denervation/or injury to
the muscle.
b) Fasciculation:- spontaneous
twitching of bundles of muscle fibers
resulting from single impulses of the cell
bodies of the motor neurons as in
poliomyelitis.

26. Rhythmic and arrhythmic
contractions
 Tremor:- Alternate, rhythmical
contraction in muscle group and their
antagonists; rigidity results.
 Coordinated grouping of the discharge
of muscle units results in the gross
tremor of shivering.
 Training produces a reduction in the
electrical activity required for a muscle
to produce a given degree of tension.

27. Contracture
Def: Prolonged resistance to passive
stretch in a muscle.
Two types:
◦ Physiological contracture
◦ Myostatic contracture
a) Physiological contracture:
Results from mechanical, chemical or
other agents acting directly on the
contractive mechanism. It occurs when a
working muscle becomes fatigued.

28. Contracture
b) Myostatic contracture:
A fibrotic condition of the supporting
connective tissues of a muscle or joint.
This could be due to prolonged
immobilization in a cast or tendon repair
or paralysis of antagonist muscle.

29. Crumps
Are involuntary sustained painful
contraction of skeletal muscle. Can occur
during sleep or exercise.
Electromyographically, they are due to
excitation of most of the muscle fibres in a
given motor unit
The pain is proportional to the total
number of active units.
Hypertrophied muscles are more liable to
crump.

30. Crumps
Causes:
i. Local fatigue
ii. Rapid change in deep muscle
temperature (exertion is not preceded
by warm up)
iii. Extreme effort when the muscle is in
shortened position
iv. Restricted circulation caused by tight
clothing or prolonged static contraction
v. Ions imbalance due to excessive
perspiration.

31. Crumps
Antidotes
i. Rest
ii. Warm up
iii. Fluid intake
iv. Acute crumps can be relieved by
contraction of the antagonist
(reciprocal inhibiting reflex)

32. Muscle Spasm
 Resemble Crumps – but is more
severe and continuously
 Persistent post exercise soreness and
low back pain may be due to spasm.

33. Spasticity:
 Proprioceptive impulses help to maintain
muscles at rest (muscle spindles) when
a ms contracts this discharge is stopped
and the ms contracts.
 A disturbance in efferent control on the
spindle may lead to continuous
discharge of impulses leading to an
exaggerated stretch reflex – Hypertonus.
If an attempt is made to move the limb,
an exaggerated motor unit activity is
observed – this is spasticity.

34. Isometric-Isotonic tension:
Isometric Contraction
When force is exerted by a muscle
against an object it cannot move, the
muscle remains the same length and
technically accomplishes no work.
Isotonic Contraction
When a muscle is able to move a load –
work is accomplished and the muscle is
said to have performed isotonic
contraction

35. Work done by muscles
 Work = force x distance
W = fd
 Negative work: eccentric contrition

36. MUSCLE CONTRACTION
Type of
tension
Type of
contraction
Function External
opposing
force
External work
ms
Energy
supply
Isotonic Concentric Acceleration Less Positive Increase
Isometric Static Fixation Equal None Same
Lengthening Eccentric Deceleration Greater Negative Decrease

37. Proprioception and
Kinesthesis
 Proprioceptors are internal receptors
located in the skin, joints muscles and
tendons
 They provide feedback with regard to
tension, length and contractile state of a
ms, the position of limbs and joint
movement
 Proprioceptors and others sense organs
are vital for Kinesthesis

38. Proprioception and
Kinesthesis
 Kinesthesis is awareness of body
position in space.
 Proprioceptors in muscles are Golgi
Tendon Organs (GTO) And Muscle
Spindles
 Muscle spindle are concentrated in the
Muscle Belly between fibres and are
sensitive to stretch and its rate. They
send impulses to the brain in stretch

39. Proprioception and
Kinesthesis
 Golgi Tendon Organs are found in the
tendons close to the muscle-Tendon
junction
 It is active in muscle tension and
contraction
 It is less sensitive to stretch than a
muscle spindle
 muscle tension activates the GTO
which consequently increases the ms
tension

40. Proprioception and
Kinesthesis
 When threshold is reached and
impulse is sent to the brain and
tension is eased. The muscle relaxes
and the antagonist is activated as a
protective mechanism
 GTO therefore protects us from
excessive contraction by causing the
muscles to relax.

41. Proprioception and
Kinesthesis
 Pacinian corpuscles around joints
capsules, ligaments, and Tendon
sheaths beneath the skin are activated
by rapid change in joint angle
 They are important in providing
feedback to location of body parts in
space

42. Proprioception and
Kinesthesis
 Meissner’s Corpuscles and
Krause’s end-bulbs are located in
the skin and the subcutaneous tissue
 Responsible for fine touch and minute
vibrations (Meissner’s) and Touch and
pressure changes (Krause’s end-
bulbs)

43. Proprioceptors - Summary
Receptor Sensitivity Location
Muscle Spindle Subconscious muscle sense Skeletal Muscle
Golgi Tendon Organ Subconscious muscle sense Tendons, ( Ms-tendon
Junction)
Pacinian Corpuscles Pressure, Vibrations Subcutaneous, around
joints and external
genitalia
Riffini’s Corpuscle Touch, Pressure Skin, Joint capsules of
fingers
Meissners Corpuscles Fine Touch, Vibrations In the skin
Krause’s end-bulb Touch, Thermal Changes Skin, Subcutaneous
tissue, lips, eyelids
mucosa, external genitals

44. Muscular Contraction and
Movement
 END

45. Proprioception and
Kinesthesis
 Raffini’s Corpuscle located deep in
the skin and joint capsule detects joint
movements and pressure changes.
 They detect minute joint positions and
provide information as to the exact
joint angle.