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Types of stretching
Just as there are different types of flexibility, there are also different types
of stretching. Stretches are either dynamic (meaning they involve motion) or
static (meaning they involve no motion). Dynamic stretches affect dynamic
flexibility and static stretches affect static flexibility (and dynamic
flexibility to some degree).
The different types of stretching are:
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Ballistic Stretching
Ballistic stretching uses the momentum of a moving body or a limb in an attempt
to force it beyond its normal range of motion. This is stretching, or "warming
up", by bouncing into (or out of) a stretched position, using the stretched
muscles as a spring which pulls you out of the stretched position. (e.g.
bouncing down repeatedly to touch your toes.) This type of stretching is not
considered useful and can lead to injury. It does not allow your muscles to
adjust to, and relax in, the stretched position. It may instead cause them to
tighten up by repeatedly activating the stretch reflex (see section The Stretch
Reflex).
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Dynamic Stretching
Dynamic stretching involves moving parts of your body and gradually increasing
reach, speed of movement, or both. Do not confuse dynamic stretching with
ballistic stretching! Dynamic stretching consists of controlled leg and arm
swings that take you (gently!) to the limits of your range of motion. Ballistic
stretches involve trying to force a part of the body beyond its range of
motion. In dynamic stretches, there are no bounces or "jerky" movements. An
example of dynamic stretching would be slow, controlled leg swings, arm swings,
or torso twists.
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Dynamic stretching improves dynamic flexibility and is quite
useful as part of your warm-up for an active or aerobic workout (such as a
dance or martial-arts class).
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Dynamic stretching exercises should be
performed in sets of 8-12 repetitions:
Perform your exercises (leg raises, arm swings) in sets of eight to twelve
repetitions. If after a few sets you feel tired -- stop. Tired muscles are less
elastic, which causes a decrease in the amplitude of your movements. Do only
the number of repetitions that you can do without decreasing your range of
motion. More repetitions will only set the nervous regulation of the muscles'
length at the level of these less than best repetitions and may cause you to
lose some of your flexibility. What you repeat more times or with a greater
effort will leave a deeper trace in your [kinesthetic] memory! After reaching
the maximal range of motion in a joint in any direction of movement, you should
not do many more repetitions of this movement in a given workout. Even if you
can maintain a maximal range of motion over many repetitions, you will set an
unnecessarily solid memory of the range of these movements. You will then have
to overcome these memories in order to make further progress.
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Active Stretching
Active stretching is also referred to as static-active stretching . An active
stretch is one where you assume a position and then hold it there with no
assistance other than using the strength of your agonist muscles (e.g. the
agonists for the Hamstrings would be the Quadriceps). For example, bringing
your leg up high and then holding it there without anything (other than your
leg muscles themselves) to keep the leg in that extended position. The tension
of the agonists in an active stretch helps to relax the muscles being stretched
(the antagonists) by reciprocal inhibition.
Active stretching increases active flexibility and strengthens the agonistic
muscles. Active stretches are usually quite difficult to hold and maintain for
more than 10 seconds and rarely need to be held any longer than 15 seconds.
Many of the movements (or stretches) found in various forms of yoga are active
stretches.
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Passive Stretching
Passive stretching is also referred to as relaxed stretching , and as
static-passive stretching . A passive stretch is one where you assume a
position and hold it with some other part of your body, or with the assistance
of a partner or some other apparatus. For example, bringing your leg up high
and then holding it there with your hand. The splits is an example of a passive
stretch (in this case the floor is the "apparatus" that you use to maintain
your extended position).
Slow, relaxed stretching is useful in relieving spasms in muscles that are
healing after an injury. Obviously, you should check with your doctor first to
see if it is okay to attempt to stretch the injured muscles.
Relaxed stretching is also very good for "cooling down" after a workout and
helps reduce post-workout muscle fatigue, and soreness.
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Static Stretching
Many people use the term "passive stretching" and "static stretching"
interchangeably. However, there are a number of people who make a distinction
between the two. According to M. Alter :
Static stretching involves holding a position. That is, you stretch to the
farthest point and hold the stretch ...
Passive stretching is a technique in which you are relaxed and make no
contribution to the range of motion. Instead, an external force is created by
an outside agent, either manually or mechanically.
Notice that the definition of passive stretching given in the previous section
encompasses both of the above definitions. |
Throughout this document, when the term static stretching or passive stretching
is used, its intended meaning is the definition of passive stretching as
described in the previous section. You should be aware of these alternative
meanings, however, when looking at other references on stretching.
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Isometric Stretching
Isometric stretching is a type of static stretching (meaning it does not use
motion) which involves the resistance of muscle groups through isometric
contractions (tensing) of the stretched muscles. The use of isometric
stretching is one of the fastest ways to develop increased static-passive
flexibility and is much more effective than either passive stretching or active
stretching alone. Isometric stretches also help to develop strength in the
"tensed" muscles (which helps to develop static-active flexibility), and seems
to decrease the amount of pain usually associated with stretching.
The most common ways to provide the needed resistance for an isometric stretch
are to apply resistance manually to one's own limbs, to have a partner apply
the resistance, or to use an apparatus such as a wall (or the floor) to provide
resistance.
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An example of manual resistance would be holding onto the ball of your foot to
keep it from flexing while you are using the muscles of your calf to try and
straighten your instep so that the toes are pointed.
An example of using a partner to provide resistance would be having a partner
hold your leg up high (and keep it there) while you attempt to force your leg
back down to the ground.
An example of using the wall to provide resistance would be the well-known
"push-the-wall" calf-stretch where you are actively attempting to move the wall
(even though you know you can't).
Isometric stretching is not recommended for children and adolescents whose bones
are still growing. These people are usually already flexible enough that the
strong stretches produced by the isometric contraction have a much higher risk
of damaging tendons and connective tissue. Kurz strongly recommends
preceding any isometric stretch of a muscle with dynamic strength training for
the muscle to be stretched. A full session of isometric stretching makes a lot
of demands on the muscles being stretched and should not be performed more than
once per day for a given group of muscles (ideally, no more than once every 36
hours).
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The proper way to perform an isometric stretch is as follows:
Assume the position of a passive stretch for the desired muscle.
Next, tense the stretched muscle for 7-15 seconds (resisting against some force
that will not move, like the floor or a partner).
Finally, relax the muscle for at least 20 seconds.
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To understand Isometric stretching we need to understand that there is no such
thing as a partially contracted muscle fiber: when a muscle is contracted, some
of the fibers contract and some remain at rest (more fibers are recruited as
the load on the muscle increases). Similarly, when a muscle is stretched, some
of the fibers are elongated and some remain at rest. During an isometric
contraction, some of the resting fibers are being pulled upon from both ends by
the muscles that are contracting. The result is that some of those resting
fibers stretch!
Normally, the handful of fibers that stretch during an isometric contraction are
not very significant. The true effectiveness of the isometric contraction
occurs when a muscle that is already in a stretched position is subjected to an
isometric contraction. In this case, some of the muscle fibers are already
stretched before the contraction, and, if held long enough, the initial passive
stretch overcomes the stretch reflex and triggers the lengthening reaction,
inhibiting the stretched fibers from contracting.
When you isometrically contracted, some of the resting fibers would contract,
many of the resting fibers would stretch, and many of the already stretched
fibers, which are being prevented from contracting by the inverse myotatic
reflex [the lengthening reaction], would stretch even more. When the isometric
contraction was relaxed and the contracting fibers returned to their resting
length, the stretched fibers would retain their ability to stretch beyond their
normal limit. ... the whole muscle would be able to stretch beyond its initial
maximum, and you would have increased flexibility ...
The reason that the stretched fibers develop and retain the ability to stretch
beyond their normal limit during an isometric stretch has to do with the muscle
spindles (see Proprioceptors): The signal which tells the muscle to contract
voluntarily, also tells the muscle spindle's (intrafusal) muscle fibers to
shorten, increasing sensitivity of the stretch reflex. This mechanism normally
maintains the sensitivity of the muscle spindle as the muscle shortens during
contraction. This allows the muscle spindles to habituate (become accustomed)
to an even further-lengthened position.
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PNF stretching is currently the fastest and most effective way known to
increase static-passive flexibility. PNF is an acronym for proprioceptive
neuromuscular facilitation . It is not really a type of stretching but is a
technique of combining passive stretching (see section Passive Stretching) and
isometric stretching (see section Isometric Stretching) in order to achieve
maximum static flexibility. Actually, the term PNF stretching is itself a
misnomer. PNF was initially developed as a method of rehabilitating stroke
victims. PNF refers to any of several post-isometric relaxation stretching
techniques in which a muscle group is passively stretched, then contracts
isometrically against resistance while in the stretched position, and then is
passively stretched again through the resulting increased range of motion. PNF
stretching usually employs the use of a partner to provide resistance against
the isometric contraction and then later to passively take the joint through
its increased range of motion. It may be performed, however, without a partner,
although it is usually more effective with a partner's assistance.
Most PNF stretching techniques employ isometric agonist contraction/relaxation
where the stretched muscles are contracted isometrically and then relaxed. Some
PNF techniques also employ isometric antagonist contraction where the
antagonists of the stretched muscles are contracted. In all cases, it is
important to note that the stretched muscle should be rested (and relaxed) for
at least 20 seconds before performing another PNF technique. The most common
PNF stretching techniques are:
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the hold-relax
This technique is also called the contract-relax . After assuming an initial
passive stretch, the muscle being stretched is isometrically contracted for
7-15 seconds, after which the muscle is briefly relaxed for 2-3 seconds, and
then immediately subjected to a passive stretch which stretches the muscle even
further than the initial passive stretch. This final passive stretch is held
for 10-15 seconds. The muscle is then relaxed for 20 seconds before performing
another PNF technique.
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the hold-relax-contract
This technique is also called the contract-relax-contract , and the
contract-relax-antagonist-contract (or CRAC ). It involves performing two
isometric contractions: first of the agonists, then, of the antagonists. The
first part is similar to the hold-relax where, after assuming an initial
passive stretch, the stretched muscle is isometrically contracted for 7-15
seconds. Then the muscle is relaxed while its antagonist immediately performs
an isometric contraction that is held for 7-15 seconds. The muscles are then
relaxed for 20 seconds before performing another PNF technique.
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the hold-relax-swing
This technique (and a similar technique called the hold-relax-bounce ) actually
involves the use of dynamic or ballistic stretches in conjunction with static
and isometric stretches. It is very risky, and is successfully used only by the
most advanced of athletes and dancers that have managed to achieve a high level
of control over their muscle stretch reflex. It is similar to the hold-relax
technique except that a dynamic or ballistic stretch is employed in place of
the final passive stretch.
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Notice that in the hold-relax-contract, there is no final
passive stretch. It is replaced by the antagonist-contraction which, via
reciprocal inhibition, serves to relax and further stretch the muscle that was
subjected to the initial passive stretch. Because there is no final passive
stretch, this PNF technique is considered one of the safest PNF techniques to
perform (it is less likely to result in torn muscle tissue). Some people like
to make the technique even more intense by adding the final passive stretch
after the second isometric contraction. Although this can result in greater
flexibility gains, it also increases the likelihood of injury.
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Even more risky are dynamic and
ballistic PNF stretching techniques like the hold-relax-swing, and the
hold-relax-bounce. If you are not a professional athlete or dancer, you
probably have no business attempting either of these techniques (the likelihood
of injury is just too great). Even professionals should not attempt these
techniques without the guidance of a professional coach or training advisor.
These two techniques have the greatest potential for rapid flexibility gains,
but only when performed by people who have a sufficiently high level of control
of the stretch reflex in the muscles that are being stretched.
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Like isometric stretching (see section Isometric Stretching),
PNF stretching is also not recommended for children and people whose bones are
still growing (for the same reasons. Also like isometric stretching, PNF
stretching helps strengthen the muscles that are contracted and therefore is
good for increasing active flexibility as well as passive flexibility.
Furthermore, as with isometric stretching, PNF stretching is very strenuous and
should be performed for a given muscle group no more than once per day
(ideally, no more than once per 36 hour period).
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The initial recommended procedure for PNF stretching is to
perform the desired PNF technique 3-5 times for a given muscle group (resting
20 seconds between each repetition). However, HFLTA cites a 1987 study whose
results suggest that performing 3-5 repetitions of a PNF technique for a given
muscle group is not necessarily any more effective than performing the
technique only once. As a result, in order to decrease the amount of time taken
up by your stretching routine (without decreasing its effectiveness), HFLTA
recommends performing only one PNF technique per muscle group stretched in a
given stretching session.
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How PNF Stretching Works
Remember that during an isometric stretch, when the muscle performing the
isometric contraction is relaxed, it retains its ability to stretch beyond its
initial maximum length (see section How Isometric Stretching Works). Well, PNF
tries to take immediate advantage of this increased range of motion by
immediately subjecting the contracted muscle to a passive stretch.
The isometric contraction of the stretched muscle accomplishes several things:
As explained previously (see section How Isometric Stretching Works), it helps
to train the stretch receptors of the muscle spindle to immediately accommodate
a greater muscle length.
The intense muscle contraction, and the fact that it is maintained for a period
of time, serves to fatigue many of the fast-twitch fibers of the contracting
muscles. This makes it harder for the fatigued muscle fibers to contract in
resistance to a subsequent stretch.
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The tension generated by the contraction activates the golgi
tendon organ (see page on Proprioception), which inhibits contraction of the
muscle via the lengthening reaction. Voluntary contraction during a stretch
increases tension on the muscle, activating the golgi tendon organs more than
the stretch alone. So, when the voluntary contraction is stopped, the muscle is
even more inhibited from contracting against a subsequent stretch.
PNF stretching techniques take advantage of the sudden "vulnerability" of the
muscle and its increased range of motion by using the period of time
immediately following the isometric contraction to train the stretch receptors
to get used to this new, increased, range of muscle length. This is what the
final passive (or in some cases, dynamic) stretch accomplishes.
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We hope this answers any questions you had regarding stretching
and the many different stretching techniques. If you require any further
information, there are many excellent books and videos available on the
subjects discussed at www.houghtonsbooks.com
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