The Achilles tendon is well known to runners.  Most of the time it is a handy piece of anatomy that allows us to absorb load when our foot hits the ground, and transmit force developed by our calf muscles to propel us forward.  Unfortunately this tendon can occasionally become painful.  Those who have experienced Achilles pain will know that it can be severe enough to completely stop training.  Moreover, it can linger on for months, even years if not managed well in the early stages.

The Achilles is the tendon that attaches the soleus (deep calf muscle) and the gastrocnemius (superficial calf muscle) to the Calcaneous (heal bone).  It is a thick, cylindrical, easily palpated tendon just above your heal bone.  If you palpate the tendon inferiorly (towards the foot), you will notice the tendon blending into the Calcaneous (heal bone) to the point where it is difficult to tell what is tendon and what is bone.  If you palpate superiorly (upward) you will notice the tendon grows thick and flat as it becomes musculotendonis (the transition from tendon to muscle).  Eventually the tendon disappears and the only tissue you will be palpating is the superficial calf – gastrocnemius.

The purpose of any tendon is two fold, each having a nuance of course.  The first is to transmit force developed by the attached muscle contraction to enable movement (the two ends of the muscle coming closer together).  For the Achilles, this is when the soleus and gastrocnemius concentrically contract (when a muscle shortens via contraction).  This contraction causes the heal to become closer the back of the knee (or toe pointing) as in the exercise heal raises. There is also a mild action to bend the knee via the gastrocnemius (as the gastroc attached above the knee).  The other mechanism is to bare load when a muscle is forced to lengthen.  For the Achilles this is when the foot hits the ground when running (or walking) and the calf muscles eccentrically contract (lengthen as they contract) to soften the heal strike and control movement of the lower leg just after the heal hits the ground.

So what goes wrong with the Achilles?  Most runners will have experienced some sort of pain associated with their Achilles.  More often than not it will be an acute episode of inflammation (swelling with inflammatory cells) that occurs due to tissue damage about the Achilles.  It is usually associated with (but not limited to) a palpable nodule on the Achilles that is very sensitive, stiffness initially in the morning but warms up as you become active and pain to hop.  Hill running will be very difficult.  If treated with (but not limited to) rest, anti-inflammatories, ice and treatment (assessment of possible causes and treatment of these), you will recover.  If you ignore the pain, the problem can become chronic.  The inflammation will disappear but the Achilles will become degenerative (the Achilles tissue will break down).  This can lead to the Achilles becoming very thickened and the calf muscles will become very weak.

So what causes this?  There are numerous causes for Achilles pain.  Start looking at the very obvious.  Has your training load increased?  Do you have very old shoes that have worn?  Brand new shoes?  Camber running or excessive hill running?  Has your dorsiflexion range of motion decreased?  Have you changed your type of training (track running, flats instead of joggers, spikes, plyometrics are all examples of what often cause acute onset Achilles pain).  You can often self assess and figure out what is causing your pain.  Change these immediately.  If you can’t see anything obvious then make a visit to your health practitioner.

What can you do?  For acute onset of Achilles pain, try to assess what has caused your pain and change that immediately.  For the Achilles itself, ice the affected area, put a heal raise in your shoe for a few days to take the load off the Achilles, cross train and gently mobilise the Achilles.  How to mobilise? 

Pincer grip (grip with forefinger and thumb) just below and just above the nodule on the Achilles, or at least the most painful portion, and bend the Achilles back and forward.  Do this for a couple of minutes at a time, three to four times a day.  This will often decrease the amount of pain felt when hopping and walking and promote recovery. 

For chronic Achilles pain, eccentric calf exercises are the most important part of treatment.  The concept is to put load through the Achilles (which is now devoid of inflammation and becoming degenerative), to create a healing inflammatory response, and more healthy connective tissue will be laid down to heal the tendon.  How to do this?  Stand on a step, heal raise on both legs, now with your body weight on the painful side, slowly allow your heel to drop below the step height, and repeat.  For a hypothetical set, try three sets of six to begin with.  Be prepared for the Achilles to initially become more painful.  This will subside and slowly the Achilles will become less painful and your typical signs and symptoms will decrease.  By all means, please consult your health practitioner if you need direction.

To prevent Achilles pain, be careful with major changes to your training method and load.  Also, do preventative exercises as suggested above, including Achilles mobilisation.

Happy running.

Anatomy
Pes Anserenus is the term given to the common attachment of three muscles that insert into the tibia, just below and medial to the knee.  These three muscles are from anterior to posterior the Sartorius, Gracilis and Semitendinosus.  All three have separate origins and separate nerve supplies but converge about the medial knee before inserting into the Pes Anserenus.

Further anatomical considerations
The origins of these three muscles are quite diverse.  Anterior (in front of) to the hip, originating from the anterior superior iliac spine (boney prominence at the front of the hip) is the sartorius.  Deep in the adductor (groin) region, originating from the inferior ramus of the pubis, is the Gracilis.  And the Semitendinosus is one of the hamstring muscles and originates from the Ischial Tuberosity (the ‘sit bone’ or the boney prominence at the base of your buttocks).  All three muscles are superficial and can be palpated easily although the Gracilis is quite difficult to identify as it is quite thin. 
Importantly, there is a bursa lying underneath the three tendons as they attach into the tibia.  Bursa are fluid filled sacks that can be found all over the body and are there to protect against two unyielding tissues frictioning on each other and causing tissue damage.  In this case the two surfaces are the three tendons (as they traverse over the medial tibia) and the boney surface of the tibia itself.

Function
As a group the sartorius, gracilis, and semitendinosus muscles are primary flexors of the knee. These 3 muscles also influence internal rotation of the tibia and protect the knee against rotary and valgus stress.
The individual function of the these three muscles is quite diverse.  In brief, the sartorius which has a nick name of the ‘tailors muscle’ acts to hip flex (bring knee towards thorax) and laterally rotate (rotate the thigh outwards) the hip, as well as flex the knee (bend the knee) and laterally rotate the tibia (outwardly rotate the lower leg).  It was called the ‘tailors muscle’ as this was the position tailors would sit in to sew.
The Gracilis is one of the long adductor group and is thought to adduct (bring towards the midline) the thigh as well as flex the thigh.
The Semitendinosus being one of the hamstring group helps extends the thigh as well as being a stabiliser of the medial thigh.

Pathologies/Injury
The Pes Anserenus is not a commonly discussed area unless there is pathology to the area.  The most common injury is to the bursa that lies under the tendons and over the tibia.  What is assumed to occur is that the friction between the tendons and the tibia becomes too much for the bursal tissue to handle and it fails and becomes inflamed.  The result is a painful, aching sensation that is sometimes red, hot and swollen (inflamed) but not always.  Running becomes painful and pain only subsides when you stop.  Rubbing the area will further inflame the area as you will be further irritating the bursal tissue.

Treatment
Depending on the severity of the bursitis, you may have to decrease or stop running for a brief to extended time to allow the bursa to settle.  Because the bursa in this area is quite superficial, topical anti-inflammatories may help.  Simply place a large dobble of gel over the painful site (don’t rub it in or you risk further irritating the bursa) and put glad wrap over the area to keep it on the focal area and off your bed sheets.  Sleep in this over night for a couple of nights.
Before diving into stretching it would be best to consult your Health Practioner.  Stretching may further compress the tendons over the angry bursa and exacerbate the problem.  Figuring out why these three tendons are creating excessive friction is necessary to objectively treat this condition.  It quite simply might be one or all three of these muscles become tight and shortened or it could be a more complex pelvis issue that your Practioner can assess and treat.

Self Treatment
Instead of stretching these muscles and risking further irritating the bursa, try self massage to these three muscles.  Use some form of cream, sorbelene for example and slowly glide your thumbs or fingers along these muscles.  Identifying them may be a bit tricky so either consult someone to help you out or go for the global approach and work the surrounding area, as close to these muscles as possible, spending time on what you palpate as tight.  Alleviating this muscular tightness may help reduce the load on the bursa that is inflamed but keep in mind that once a bursa is angry, they tend to take a while to settle down.  And note, if self massage to these muscles makes things worse, stop and consult your Health Practioner.
Cortisone may be an option for persistent Pes Anserenus bursitis.  Clinically this type of cortisone injection shows excellent results but of course; try your conservative treatment first.

Summary
Your Pes Anserenus is the attachment of three thigh muscles that traverse from the pelvis to the medial lower knee.  The bursa that stops over frictioning of the tendons over the tibia may become inflamed if the friction is excessive.  Sort advice before stretching but certainly self massage the muscles involved.

Happy running.