Flexibility
is the range of possible movement in a joint and its surrounding muscles.
The full range of movement in a joint is called the Range of Motion
(ROM).
Factors affecting Flexibility:
- Joint Structure
- the type of joint determines its ROM.
- Muscle Bulk
- excessive bulk can limit ROM.
- Age and Gender
- In general the young are more flexible than the old and females
more flexible than males.
- Connective
Tissue - tendons, ligaments, joint capsules and the skin effect
ROM.
- Frequency
of Stretching
- Activity
level - active people tend to be more flexible than sedentary
people.
When should
you stretch?
- Before exercise,
practice or competition (after an aerobic muscle warm up).
- After exercise
(as part of a warm down to increase/develop mobility).
Stretch Reflexes
There are two
proprioceptors that act to elicit the two stretch reflexes:
- The muscle
spindles are sensory mechanisms situated within muscles running
parallel with normal muscle fibres. They monitor changes in the
length of the muscle. Rapid stretching of the muscle stimulates
the muscle spindle and its sensory neuron. This in turn innervates
a motor neuron in the spinal cord, which causes a contraction
of muscle that was stretched - this is the (myotatic) stretch
reflex - This is why we should not bounce
when stretching.
- The Golgi
Tendon Organ responds to changes in the length of the muscle and
muscle tension. This prevents overstressing of the muscle as a
result of overstretching or active contraction. A contraction
of the agonist will lead to a reflex relaxation of the antagonist.
This is called reciprocal inhibition - This
means regular stretching is essential to get the muscle sequence
correct.
Types of
Stretching
- Active Stretch
- This occurs when the person doing the stretch applies the force
of the stretch.
- Passive Stretch
- This occurs when a partner or device provides the force for
the stretch. Proprioceptive Neuromuscular Facilitation (PNF) is
one example.
- Ballistic
Stretch - This involves a contra-indicated bouncing movement and
is very limited in its use.
- Dynamic Stretch
- Involves flexibility during sport specific movements. E.g. a
hurdlers stretch.
How long
should you hold a stretch for?
To warm up about
10 seconds is sufficient and to develop flexibility, at least 20
seconds, is necessary.
Benefits
of Stretching
In general,
PNF, static, and dynamic stretching stretches muscles, muscle sheaths
and tendons adequately in preparation before a workout. They also
increase ROM in joints and decrease the risk and potential severity
of injury.
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