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Flexibility training is perhaps the most undervalued component of
conditioning. While recent and ongoing debate questions its role in injury
prevention, athletes can still gain much from a stretching regime.
From a volleyball spike to a rugby drop
kick, flexibility of the body’s muscles and joints plays an integral part
in many athletic movements. |
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In general terms, flexibility has been defined
as the range of motion about a joint and its surrounding muscles during a
passive movement. Passive in this context simply means no active muscle
involvement is required to hold the stretch. Instead gravity or a partner
provides the force for the stretch.
The Benefits of Flexibility Training
By increasing this joint
range of motion, performance may be enhanced and the risk of injury
reduced. The rationale for this is that a limb can move further before an
injury occurs.
| Tight neck muscles for example, may restrict
how far you can turn your head. If, during a tackle, your head is forced beyond
this range of movement, it places strain on the neck muscles and tendons. |
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Ironically, static stretching just prior
to an event may actually be detrimental to performance and offer no
protection from injury. The emphasis is on "may" however, as a closer
examination of the scientific literature shows that effects are often minimal
and by no means conclusive.
Muscle tightness, which has been
associated with an increased risk of muscle tears, can be reduced before
training or competing with dynamic stretching. For this reason many coaches now
favor dynamic stretches over static stretches as part of the warm up.
| Competitive sport can have
quite an unbalancing effect on the body. Take racket sports for example. The
same arm is used to hit thousands of shots over and over again. One side of
the body is placed under different types and levels of stress compared to
the other. The same is true for sports like soccer and Australian Rules
football, where one kicking foot is usually dominate. A flexibility training
program can help to correct these disparities preventing chronic, over-use
injury. |
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Of course, a more flexible athlete is a more
mobile athlete. It allows enhanced movement around the court or field with
greater ease and dexterity. Some other benefits may include an increase in body
awareness and a promotion of relaxation in the muscle groups stretched - both of
which may have positive implications for skill acquisition and performance.
| A number of
anatomical and physiological factors influence an athlete's flexibility.
While some we are stuck with (such as age, gender, and joint structure),
others are under our control. These include activity level, muscle bulk
and stretching exercises. |
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The Physiology of Flexibility
1. Joint Structure
There are several different types of
joints in the human body. Some intrinsically have a greater range of motion
(ROM) than others. The ball and socket joint of the shoulder for example, has
the greatest range of motion of all the joints and can move in each of the
anatomical planes. Compare the shoulder joint to the ellipsoidal joint of the
wrist. It moves primarily in the sagittal and frontal planes. The hinge joint of
the ankle is similar while the modified hinge joint of the knee allows ROM in
the sagittal plane.
2. Age & Gender
ROM and flexibility decreases with age.
This is due, in part to the fibrous connective tissue that takes the place of
muscle fibers through a process called fibrosis. Females tend to be more
flexible than males. Older individuals should take encouragement that, just
as with strength and endurance, flexibility can be increased at any age with
training.
3. Connective Tissue
Deep connective tissue such as fascia and
tendons can limit ROM. In particular, two characteristics of connective tissue,
elasticity and plasticity are related to ROM. Elasticity is defined as the
ability to return to the original resting length after a passive stretch.
Plasticity can be defined as the tendency to assume a new and greater length
after a passive stretch. Ligaments do not seem to display any elastic
properties. However, with exposure to stretching they may extend to a new
length. The strength and conditioning coach must remember that increased
mobility in the ligaments reduces the stability of the joint - often an
unfavorable adaptation, particularly in contact sports.
4. Muscle Bulk & Weight
Training
Hypertrophy of skeletal muscle can
adversely affect ROM. It may be difficult for very bulky athletes to complete
certain stretches such as an overhead triceps stretch. However, in these
athletes, significant muscle mass is usually more favorable to their sport than
extreme ROM.
Resistance
training can increase flexibility although when heavy loads are used within a
limited ROM, weight training can reduce flexibility.
5. Proprioceptors
The capacity of the neuromuscular system
to inhibit the antagonists (those muscles being stretched) influences
flexibility.
There are
two important proprioceptors involved in the mechanics of stretching and
flexibility. The first is the muscle spindles. Located within the muscle fibers
they monitor changes in muscle length. The stretch reflex is the body’s
involuntary response to an external stimulus that stretches the muscle and
causes a reflexive increase in muscular activity. It is the muscle spindles that
activate this response.
When stretching, it is
best to avoid activating the muscle spindles and the stretch-reflex response, as
it will limit motion.
Static stretching does not elicit the muscle
spindles, allowing muscles to relax and achieve a greater stretch.
The other important proprioceptors are the golgi tendon organs (GTO). These are
located near to the musculotendinous junctions and are sensitive to increase in
muscle tension. When the GTO is stimulated it causes a reflexive relaxation in
the muscle. When this relaxation occurs in the same muscle that is being
stretched, it is referred to as autogenic inhibition and can facilitate
the stretch.
Autogenic inhibition can be induced by
contracting a muscle immediately before it is passively stretched – a technique
used in PNF stretching.
Reciprocal inhibition occurs when
the GTO is stimulated in the muscle opposite to that being stretched (i.e. so
the opposing muscle relaxes). This can be achieved by simultaneously contracting
the opposing muscle group to the one being passively stretched. 6. Internal Environment
The athlete's internal environment affects ROM. For example, mobility is
decreased immediately upon waking after a night's sleep. Ten minutes in a warm
bath increases body temperature and ROM.
7. Previous Injury
Injuries to muscles and connective tissue can lead to a thickening, or
fibrosing on the affected area. Fibrous tissue is less elastic and can lead
to limb shortening and reduced ROM. Fibrous nodules in connective tissue and
muscle are often called trigger points.A technique called myofascial
release may be able to alleviate pain and restriction caused by trigger points.
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