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Protect the Hamstrings in Forward
Bends
If its too late for this article... Read about
How to Recover from Upper Hamstring
Tendon Injuries.
Help your students avoid injuries in forward bends by
deepening your knowledge of the anatomy of the hamstring and the risk factors
for overstretching the hamstring tendon.
By Roger Cole
Perhaps you’ve felt it. Standing with straight legs, you bend forward into
Uttanasana (Standing Forward Bend), and immediately sense a nagging pain over
one of your sitting bones. If you bend the knee on that side, the pain
diminishes or disappears, but as soon as you straighten it again, the pain comes
back. As you start to exit the pose, the pain momentarily worsens, but then
disappears as you go higher. Thinking back, you realize that this has been going
on for--can it be--a year and half already?
What you are feeling is probably a partial tear in one of the two short tendons
that connect the hamstring muscles to the sitting bone. It may be right at the
bone, at mid-tendon, or at the junction where the tendon merges into the muscle.
If the injury is old, chances are you are working not only with tendon, but with
scar tissue as well.
The anatomy of this injury is quite simple. You have three hamstring muscles.
The upper end of each of them attaches to the sitting bone (ischial tuberosity).
Two of the hamstrings (semitendinosus and biceps femoris) share a single, short
tendon that joins them to the sitting bone. The third (semimembranosus) has its
own short tendon. The lower ends of all three hamstrings attach just below the
knee. When these muscles contract they bend the knee and extend the hip joint.
To stretch them effectively, a student must simultaneously straighten the knee
and flex the hip joint.
This is just what happens in Uttanasana and other straight-legged forward bends:
the knee straightens and the hip joint flexes. This moves the sitting bone away
from the back of the knee and lengthens the hamstring muscles. Hamstrings are
strong muscles, so it can take a lot of force to stretch them. When the force is
more than the tendon can bear, the tendon partially tears at or near the sitting
bone. (Other types of hamstring injuries are also possible, including mild or
severe damage to muscle, tendon, or bone caused by strong, hard muscle
contraction. This article will focus only on mild or moderate partial tears of a
hamstring tendon caused by over-stretching.)
In order to protect your students from an injury in a hamstring tendon, you need
to understand what puts them at risk for such injuries. Stretching too hard
is an obvious factor. It is especially likely to cause injury if you physically
push a student into a stretch, so be sure to avoid this.
Stretching too fast, without proper awareness, can also lead to injury.
When a student stretches too quickly, it can cause a reflex contraction of the
hamstrings which makes the muscles that are supposed to lengthen shorten
instead. Students whose muscles are both strong and tight are especially at risk
for this kind of injury.
Stretching while cold may increase risk, because a cold tendon is less
flexible and has less blood flow than a warm one. But stretching while hot
and fatigued (for example, at the end of a long, vigorous workshop) may also
be risky. The heat may make the connective tissue in the tendon so flexible that
its molecular structure can be torn apart by vigorous stretching. In addition,
the fatigue makes it more difficult for the student to monitor and control the
degree of stretch.
Another major risk factor is weak hamstring tendons. This is often a
result of habitual over-stretching and insufficient strength of the hamstring
muscles (weak muscles and weak tendons go together, because activities that
strengthen the muscles also strengthen the tendons). Habitual overstretching
comes from an excessive practice of daily forward bends with insufficient
recovery time in between. This can break down collagen molecules (the building
blocks of the tendon) faster than the body can replace them. Yoga teachers are
especially at risk for this, because they often maintain a strenuous personal
practice and also demonstrate forward bends day after day in their classes.
Stretching unevenly can also place a hamstring tendon at risk. For
example, if the semimembranosus muscle is significantly tighter than the other
two hamstrings, its tendon will receive most of the stretching force that would
normally be distributed evenly among all three hamstrings. Likewise, certain
combinations of rotation and bend at the hip or knee joints can focus excessive
stretch on a small part of a hamstring tendon, or can pull a tendon at an angle
that tends to separate it from the sitting bone.
One of the most frustrating things about a hamstring tendon injury near the
sitting bone is that it persists for so long. Tendons have a much poorer blood
supply than muscles, so when you tear them, they heal much more slowly. Students
very often try to stretch their way out of the injury too soon, too hard, or too
often. This not only slows the healing process, it also produces excessive scar
tissue. Scars don’t stretch well, so later stretching in the same area can put
excessive strain on the intact tendon fibers surrounding the scar, causing
additional injury. This, in turn, produces more scar tissue, leading to a
vicious cycle of progressively worsening injury.
The healing process after a tendon tear can be roughly divided into three
phases: inflammation, repair, and remodeling. By understanding what happens in
each of these stages, you will be better prepared to give your students advice
on what to do and when to do it.
When a student first tears a tendon, many of the tiny blood vessels
(capillaries) that feed it are destroyed. During the first 72 hours after injury
(the inflammation phase), the body’s main job is to stop bleeding, clear away
damaged tissue, prevent infection and lay the ground work for later repair.
Stressing the area with stretching or strengthening exercises during this time
will only further tear the tendon and its capillaries, undoing much of the work
the body has done and making the injury more severe.
If the inflammation phase is allowed to run its course without disturbance, the
body will enter the repair phase, which lasts six weeks or so. It begins this
phase by setting up a delicate molecular and cellular matrix that serves as the
framework for reconstructing capillaries and connective tissue. It then starts
the initial stages of filling in this matrix.
A healthy tendon is made of collagen fibers arranged in an orderly way, making
it strong and somewhat flexible in the direction of pull applied to it. However,
at the beginning of the repair phase, the body lays down new collagen fibers
haphazardly. This is a crucial time. If the student systematically applies very
mild force along the lines of the healing tendon (by practicing extremely gentle
strengthening and stretching asanas), the collagen matrix will become aligned in
an appropriate way. The body will then lay down new fibers of the right type and
connect them to one another in the optimal orientation to produce a strong,
slightly flexible tendon. If, instead, the student does not apply any stress to
the tendon after the body lays down the initial collagen fibers, the body will
continue to lay down new fibers haphazardly, and connect them randomly. The
result will be a weak, thick, inflexible scar.
Another potential problem might arise if the student stresses the healing tendon
too much by practicing asanas that demand more than just a little stretch or
contraction of the hamstrings. If that occurs, the matrix will break down, the
tendon may tear more, and the student will be thrown back to square one of the
healing process (inflammation), quite possibly with a more severe injury than
the original one.
The people who have the hardest time avoiding excessively stretching an injured
hamstring are yoga teachers themselves. Many yoga teachers instinctively feel
that they can "stretch their way out" of the injury, so they do too much too
fast. They are often reluctant to give up the vigorous practice they love and
the busy teaching schedule that earns their livelihood. They feel that to teach
properly, they must demonstrate hamstring stretches to their students. Even
those who back off from strong hamstring stretches at first often re-introduce
them as soon as they start feeling better, which is usually too soon.
Of course, the best way to deal with hamstring injuries is to prevent them from
happening in the first place. There are many ways to do this. The most important
is to never push your students into hamstring stretching poses. The second most
important is to instruct students never to push themselves to the point of pain
at the sitting bones, especially in forward bends. Instead, help your students
develop strong, stretch-tolerant hamstring tendons by systematically including
asanas that strengthen the hamstring muscles in both the shortened and
lengthened positions (see How to Recover from Upper Hamstring Tendon Injuries).
When students are cold, start them with warming poses, including mild hamstring
stretches such as Adho Mukha Svanasana (Downward-Facing Dog), before more
extreme hamstring poses. Guide students to stretch consciously, and urge them to
use extra care when their muscles are hot or fatigued. Teach good alignment to
build tendon strength and flexibility in the desired direction and to distribute
the stretching load evenly over the hamstrings tendons rather than focusing it
on a single spot.
If a student has a known hamstring injury, or if you suspect one because she
feels pain at or near the sitting bone in forward bends, urge her to immediately
stop doing any pose that creates the pain and strictly follow the recovery
advice. Advise her that such injuries must be taken seriously and "babied" for
at least several months before she should return to a full practice. Finally, if
you are dealing with this problem yourself, take heart. With patience and
diligence, there is hope for hamstrings.
Read about How to Recover from Upper
Hamstring Tendon Injuries.
Roger Cole, Ph.D. is an Iyengar-certified yoga teacher (www.yogadelmar.com),
and Stanford-trained scientist. He specializes in human anatomy and in the
physiology of relaxation, sleep, and biological rhythms.
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