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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:
passive (or relaxed) 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).
Dynamic stretching, according to Kurz, "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.
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). See section Warming Up.
According to Kurz, dynamic stretching exercises should be performed
in sets of 8-12 repetitions. Be sure to stop when and if you feel
tired. Tired muscles have less elasticity which decreases the range of
motion used in your movements. Continuing to exercise when you are
tired serves only to reset the nervous control of your muscle length at
the reduced range of motion used in the exercise (and will cause a loss
of flexibility). Once you attain a maximal range of motion for a joint
in any direction you should stop doing that movement during that
workout. Tired and overworked muscles won't attain a full range of
motion and the muscle's kinesthetic memory will remember the repeated
shorted range of motion, which you will then have to overcome before
you can make further progress.
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 (see section Cooperating Muscle Groups). 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 (see section 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
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 (see section Pain and Discomfort).
Relaxed stretching is also very good for "cooling down" after a workout
and helps reduce post-workout muscle fatigue, and soreness.
See section Cooling Down.
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 consists of stretching a muscle (or group of muscles)
to its farthest point and then maintaining or holding that position,
whereas Passive stretching consists of a relaxed person who
is relaxed (passive) while some external force (either a person or
an apparatus) brings the joint through its range of motion.
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.
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
(see section Types of Muscle Contractions). 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.
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).
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.
Some people seem to recommend holding the isometric contraction for
longer than 15 seconds, but according to SynerStretch (the
videotape), research has shown that this is not necessary. So you might
as well make your stretching routine less time consuming.
Recall from our previous discussion (see section How Muscles Contract)
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 (see section What Happens When You Stretch). 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
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 (see section The Stretch Reflex) and triggers
the lengthening reaction (see section The Lengthening Reaction), inhibiting
the stretched fibers from contracting. At this point, according to
SynerStretch, when you isometrically contracted, some resting
fibers would contract and some resting fibers would stretch.
Furthermore, many of the fibers already stretching may be prevented
from contracting by the inverse myotatic reflex (the lengthening
reaction) and would stretch even more. When the isometric contraction
is completed, the contracting fibers return to their resting length but
the stretched fibers would remember their stretched length and (for a
period of time) retain the ability to elongate past their previous
limit. This enables the entire muscle to stretch beyonds its initial
maximum and results in 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 section 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.
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
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:
- 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
- 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.
- 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 (see section The 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.
Notice that in the hold-relax-contract, there is no final passive
stretch. It is replaced by the antagonist-contraction which, via
reciprocal inhibition (see section 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.
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.
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).
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
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
The isometric contraction of the stretched muscle accomplishes several
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 (see section Fast and Slow Muscle Fibers). This makes
it harder for the fatigued muscle fibers to contract in resistance to a
subsequent stretch (see section The Stretch Reflex).
The tension generated by the contraction activates the golgi tendon
organ (see section Proprioceptors), which inhibits contraction of the muscle
via the lengthening reaction (see section 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)
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