Stretching involves lengthening muscles and connective tissues to improve flexibility and range of motion. There are several types of stretching including static, dynamic, and PNF stretching. Static stretching is a slow, controlled stretch held for 15-30 seconds. Dynamic stretching uses repetitive motions to increase range of motion. PNF stretching combines contraction and relaxation of muscles. The document provides details on the physiological effects and mechanisms of different stretching techniques.

1. STRETCHING
By:
DR: HANAA SAMIR

2. • Stretching is a physical exercise that requires putting a body part in a
certain position that'll serve in the lengthening and elongation of the
muscle or muscle group and thus enhance its flexibility and elasticity.
• Stretching is a general term used to describe any therapeutic
maneuver designed to increase the extensibility of soft tissue and
improving flexibility by elongating shortened structures
Effects of Stretching
• Improves flexibility delaying impaired mobility associated with aging
• Improves performance in physical activities as a result of improved
flexibility
• Reduce the risk of injury and damage
• Improves blood circulation reducing muscle soreness and time for
recovery
• Increasing the range of motion

3. Mechanisms of Stretching
• The stretching of a muscle fiber begins with the sarcomere, the basic unit of
contraction in the muscle fiber. As the sarcomere contracts, the area of overlap
between the thick and thin myofilaments increases. As it stretches, this area of
overlap decreases, allowing the muscle fiber to elongate. Once the muscle fiber is
at its maximum resting length (all the sarcomeres are fully stretched), additional
stretching places force on the surrounding connective tissue. As the tension
increases, the collagen fibers in the connective tissue align themselves along the
same line of force as the tension. Therefore when you stretch, the muscle fiber is
pulled out to its full length sarcomere by sarcomere, and then the connective
tissue takes up the remaining slack. When this occurs, it helps to realign any
disorganized fibers in the direction of the tension. This realignment is what helps
in the rehabilitation of scarred tissue.
• The initial changes that are produced by stretch training involve mechanical
adaptations that are followed by neural adaptations, which contrasts with the
sequence observed during strength training.
• When a muscle is stretched, some of its fibers lengthen, but other fibers may
remain at rest. The more fibers that are stretched, the greater the length
developed by the stretched muscle.

4. • Proprioceptors: The proprioceptors related to stretching are located
in the tendons and in the muscle fibers.
• Muscle Spindles (intrafusal fibers) lie parallel to the extrafusal fibers.
Muscle spindles are the primary proprioceptors in the muscle.
• Another proprioceptor that comes into play during stretching is
located in the tendon near the end of the muscle fiber and is called
the golgi tendon organ.
• A third type of proprioceptor, called a pacinian corpuscle, is located
close to the golgi tendon organ and is responsible for detecting
changes in movement and pressure within the body
• What about autogenic inhibition and reciprocal inhibition
???

5. The Stretch Reflex
• When the muscle is stretched, so is the muscle spindle. The muscle
spindle records the change in length (and how fast) and sends signals
to the spine which convey this information. This triggers the stretch
reflex which attempts to resist the change in muscle length by causing
the stretched muscle to contract. The more sudden the change in
muscle length, the stronger the muscle contractions will be
(plyometric training is based on this fact). This basic function of the
muscle spindle helps to maintain muscle tone and to protect the body
from injury. One of the reasons for holding a stretch for a prolonged
period of time is that as you hold the muscle in a stretched position,
the muscle spindle habituates and reduces its signalling. Gradually,
you can train your stretch receptors to allow greater lengthening of
the muscles

6. Flexibility:
• Flexibility is the ability to move a single joint or series of joints
smoothly and easily through an unrestricted, pain-free ROM.
• Muscle length in conjunction with joint integrity and the extensibility
of periarticular soft tissues determine flexibility. Flexibility is related
to the extensibility of musculotendinous units that cross a joint, based
on their ability to relax or deform and yield to a stretch force. The
arthrokinematics of the moving joint (the ability of the joint surfaces
to roll and slide) as well as the ability of periarticular connective
tissues to deform also affect joint ROM and an individual's overall
flexibility. Dynamic and Passive Flexibility

7. Hypo-mobility:
• Hypo-mobility refers to decreased mobility or restricted motion. A
wide range of pathological processes can restrict movement and
impair mobility. There are many factors that may contribute to hypo-
mobility and stiffness of soft tissues, the potential loss of ROM, and
the development of contractures.
Indications
• Improves the joint range of motion
• Improves posture by strengthening the back muscles
• Returns normal neuromuscular balance between muscle groups
• Reduce injuries, strains and damage
• Before and after exercise to reduce muscle soreness

8. Contraindications to Stretching:
• A bony block limits joint motion.
• There was a recent fracture, and bony union is incomplete.
• There is evidence of an acute inflammatory or infectious process (heat and
swelling) or soft tissue healing could be disrupted in the tight tissues and
surrounding region.
• There is sharp, acute pain with joint movement or muscle elongation.
• A hematoma or other indication of tissue trauma is observed.
• Hypermobility already exists.
• Shortened soft tissues provide necessary joint stability structural stability or
neuromuscular control.
Shortened soft tissues enable a patient with paralysis or severe muscle
weakness to perform specific functional skills otherwise not possible.

9. Determinants of Stretching Interventions:
• Alignment: positioning a limb or the body such that the stretch force
is directed to the appropriate muscle group

10. • Stabilization: fixation of one site of attachment of the muscle as the
stretch force is applied to the other bony attachment. Usually
stabilize proximal and stretch distal. The opposite with self stretching.

11. • Intensity of stretch: magnitude of the stretch force applied- low intensity
long duration stretching is the most effective in improving ROM
• The lower the intensity of stretch the longer the time the patient can
tolerate stretching
• Inverse relationship between intensity and duration also between intensity
and frequency of stretching.
• Duration of stretch: length of time the stretch force is applied during a
stretch cycle. In general the shorter the duration of stretch cycle the greater
the number of repetitions during the session.
• Speed of stretch: speed of initial application of the stretch force •
Frequency of stretch: number of stretching sessions per day or per week
• Mode of stretch: form or manner in which the stretch force is applied
(static, ballistic, cyclic); degree of patient participation (passive, assisted,
active); or the source of the stretch force (manual, mechanical, self)

12. • Manual stretching and self-stretching in hypomobile but healthy
subjects and prolonged mechanical stretching in patients with chronic
contractures yield significant stretch-induced gains in ROM.
• In the well elderly, stretch cycles of 15, 30, and 60 seconds applied to
the hamstrings for four repetitions have all been shown to produce
significant gains in ROM with the greatest and longest- lasting
improvements occurring with the use of 60-second stretch cycles.
• In healthy young and/or middle-age adults
• Stretch durations of 15, 30, 45, or 60 seconds or 2 minutes to lower
extremity musculature produced significant gains in ROM.
• Two repetitions daily of a 30-second static stretch of the hamstrings
yield significant gains in hamstring flexibility similar to those seen
with six repetitions of 10-second static stretch daily.

13. • There seems to be no additional benefit to holding each stretch cycle
beyond 60 seconds.
• Three cycles of 30-second and 1-minute stretches are no more
effective for improving ROM than one cycle of each duration of
stretch.
• When the total duration of stretch is equal, cyclic stretching is equally
effective and possibly more comfortable than static stretching.
• For older adults, the duration of static stretching should be longer to
notice improvements. For example, a sixty-second hold stretch served
in an increase by 2 degrees per week in range of motion while a thirty
-second hold stretch served in an increase by 1 degree

14. Types of stretching
Static Stretching
• Static stretching (SS) is a slow-paced controlled physical activity which
involves putting the body part in a comfortable position that
elongates the muscle without causing pain with low force for a
prolonged duration of time (usually 30 seconds).
• There are two types of static stretching:
1- Active-static stretching(self) involves performing static stretches
without assistance (Added force is applied by the individual for greater
intensity).
2- Passive-static stretching involves performing the stretches passively
with assistance from an external force which can be a partner, an
accessory or the force of gravity.

15. A- manual passive stretching:
Both contractile and non contractile tissues can be elongated by
passive stretching.
- The therapist applies external force and controls the direction, speed
and duration of stretch to soft tissues. The tissues are elongated
beyond their resting length.
- This technique should not be confused with passive range of motion
exercises as passive stretching takes the structures beyond the free
range of motion. passive ROM is applied only within the unrestricted
range.
- The stretching force is usually applied for at least 15 to 30 seconds
and repeated several times.

23. Dynamic Stretching
• Dynamic Stretching (DS) is a controlled movement, unlike ballistic stretches that
involve bouncing movements which increase the risk of injury, involving the
performance of a movement progressively increasing the range of motion through
successive repetitive motions till the end of the range is achieved. It can be done
standing or while moving.
• For individuals who perform specific sports such as swimming, dynamic stretching
exercises involve mimicking the movement of the activity such as circling arms
before getting in the water and is often done after static stretching.
• Effects of dynamic stretching:
• Restore physical functioning and flexibility
• Improve neuromuscular control through repetitive movement which: enhance the
nervous message conduction speed, motor control and muscle compliance
• Elevates core body temperature
• Accelerates energy production
• Improves performance measures such as speed and strength

24. • Maintained static versus ballistic stretch:
When manual passive stretching is applied the stretch is slow and
gentle. It is maintained 15-30 sec. ballistic stretching very short
duration (bouncing) stretch. It is an inappropriate way to stretch
muscle. It quickly lengthens the muscle spindle and facilitate stretch
reflex causing an increase in tension of the muscle being elongated.
Muscles are more susceptible to micro trauma with ballistic stretching
as the tension produced in the muscles is twice that created with low
intensity maintained stretch.

25. Pre-Contraction Stretching: Proprioceptive
Neuromuscular Facilitation Stretching (PNFS)
• Pre-contraction stretching is a type of stretching that involves both the
contraction and stretching of the muscle. It has been originally developed for the
sole reason of relaxing muscles and increasing muscle tone.
• The most common type is PNF, proprioceptive neuromuscular facilitation, which is
a technique which can be performed in different ways. One of which is the
contract-relax method during which the muscle is held in a stretching position by
a partner and the person contracts the muscle for a minimum of 4 seconds
followed by a short relaxation period of two to three seconds. The stretch should
progressively be pushed further than the initial stretch and held for a longer
period of time(held for a minimum of 10 seconds and relaxed for 20 seconds).
Another would be hold-relax method which involves putting the muscle in a
stretched position first by a partner and then the partner contracts the muscle
while asking the person to prevent this contraction and afterwards passive stretch
of the muscle is applied by the partner. A different method would be the contract-
relax agonist contract during which the muscle is also elongated by the partner for
a minimum of 4 seconds and the person is asked to contract the agonist of the
muscle then activate the antagonist of the muscle followed by a relaxation period
of 20 seconds