Biceps Femoris

Anatomy
The biceps femoris (long head) is one of the hamstring group.  It has it’s origin on your Ischial tuberosity (base of your buttock/top of your hamstring) or what is often called your ‘sitting bone’.  Its insertion is on the head of your fibula, just below and lateral to your knee (a palpable boney protuberance).  There is a short head of your biceps femoris that originates at the distal (lower) portion of your femur (thigh bone) and inserts into the same fibula head.  We will discuss the long head of the biceps femoris.

Further anatomical considerations
There is some other important information regarding the biceps femoris anatomy.  At its origin, it lies just medial (to the middle) of the sciatic nerve.  It also has a close relationship to the sciatic nerve as it traverses through the hamstring.  With this in mind, these two structures are often in cohort when pain occurs.  Furthermore, the biceps femoris has a direct relationship with a large ligament in your gluteal region called your sacrotuberous ligament (a ligament that generally attaches your ischial tuberosity to your sacrum [bone at base of spine]).  Hence, it is difficult to isolate the biceps femoris in its function and pathology due to its close and integrated relationship with these structures.

Function
The biceps has two basic functions of flexing the knee (bending the knee) and extending the hip (propelling your thigh behind your body).  Because of its direction of fibers and its anatomical set up and relationship to other structures, it is often described as a ‘force transfer’ hamstring (in comparison to a stability hamstring).  Hence, it bears considerable load when you are trying to develop force when running and is therefore vulnerable to load bearing injury and strain.

Pathologies/Injury
The biceps femoris is by far the most strained hamstring.  This occurs mostly when developing explosive force when running, hence not a typical injury for the distance runner.  It does however become involved with injury relating to the sciatic nerve due to its close anatomical relationship.  A common injury for distance runners is a ‘tethering’ (stickiness between two structures, usually relating to nerve) of the sciatic nerve to the upper portion of your biceps femoris.  This ends in pain about the base of your buttock (top of your hamstring) that can cause nerve type pain radiating down your leg.  If you experience this type of pain, you will need to have it assessed immediately as this injury can become chronic and WILL stop you running for a very prolonged period, if not stop you running.  Early intervention (stretching regimes, treatment of the soft tissues, alteration of your posture and gait, nerve related stretches) will help remedy the situation.  Prolonged pain may end in injection measures or even surgery to remove the scar formation from the biceps femoris and sciatic nerve (to allow them to slide normally past each other)
Again, due to anatomical set up of this muscle, any load that is born about your lumbar spine, mid back (just for example) can and will end in extra load on your biceps femoris.  This may end in a tendonitis (inflammation) and/or tendinosis (tendon degeneration).  If you have this type of pain, you will need to have more than just your biceps femoris assessed.  All other structures that are involved with this muscle group will need to be assessed, including a functional assessment of your gait if necessary.

Self Treatment
Obviously regular stretching of this muscle is a necessity.  I wouldn’t attempt to gain extra length in this muscle as a degree of stiffness actually helps propel you (elastic energy development).  I would however mildly stretch it, on a regular basis, to alleviate any pain restriction as well as using the stretch to assess whether or not it has become extra ‘stiff’ due to training or racing.  In this situation, you will simply stretch to regain what is your usual flexibility.
Self massage with a tennis ball is a simple to use modality.  Place the tennis ball under your leg (under your biceps femoris) while sitting on a chair.  You can simply apply force by applying body weight (looking for trigger points for example) or you can extend your leg while in this position which creates a focused stretch where the ball is place (giving you the ability to alleviate focal stiffness within your biceps femoris).

Summary
Your biceps femoris is a vital muscle in running.  It helps propel you, it controls your leg and eventually foot when it lands, it is a vital lynch pin in the way your body transfers force when running.  Get to know them, look after them.

Happy running.

Great information.  I should get on this website more often

Your biceps femoris theory sounds interesting and is amusing. But I gues, the euphoria this 646-003 machine gives you have got nothing to do with your biceps femoris. I think the pleasure comes from your testicles getting rubbed contantly by your muscles.