Do you think you have tight hamstrings?, Part 1: Understanding Anatomy

This topic series is meant to be applied holistically to any group of “tight” muscles. In this topic series we will be exploring why a muscle may develop tightness, using the hamstrings as an example.

Has a client told you that they have tight hamstrings before? Are your clients unable to bend forward and touch their toes because of “tight” hamstrings? What if I told you that the hamstrings may not be “tight”, but rather they are overstretched and compensating for dysfunction else where?

In order to understand why the hamstrings get “tight” we need to understand it’s anatomy first.


The hamstring is a group of muscles including the biceps femoris (long and short head), semitendinosus, semimembranosus. All aspects of the hamstring originate off of the ischial tuberosity except for the short head of the biceps femoris, which originates from the linea aspera of the femur.  The semitendinosus and semimembranosus run along the medial portion of the posterior leg and attach to the medial portion of the knee. The biceps femoris attach to the lateral aspect of the fibular head.

When other muscles in the hip get tight, they can anteriorly rotated our pelvis and put our hamstrings on stretch at rest. Our muscles can operate and contract throughout an entire range, but work optimally within a certain range. When our muscles are too stretched out they are ineffective and when they are too contracted, they become inefficient. This is called the length-tension relationship.

length tension relationship.jpg

In the above graph, 3 and 4 represent ranges where the muscle is too stretched out – the myosin and actin fibers do not overlap enough to pull effectively – and cannot contract effectively. 1 represents ranges where the muscle is already contracted – too much overlap between the myosin and actin, so it is not able to contract any further – this is often an explanation for muscle cramps; your muscles are already operating in a shortened range and it is unable to further contract, therefore it cramps up during a movement. 2 represents the optimal range for muscle contraction. This concept of “optimal muscle length” is an important one for all movement and can sometimes be forgotten in the clinical world while treating clients.

lateral ant tilt view

This is a lateral view where the L is “anterior” and the R is “posterior”. The image on the Left is normal pelvis positioning (neutral). The image on the Right is a forwardly tipped pelvis (anteriorly rotated). In the image on the Right, the hamstrings already “pre-stretched”. Many people judge whether or not they have tight hamstrings based on whether or not they can bend forward and touch their toes or sit with their legs in front of them and try to touch their toes. If they can’t, they deem themselves as having “tight” hamstrings. But what if your pelvis was rotated forward? Your hamstrings would be “stretched” at the start before your bend forward, and therefore it is unable to stretch much further.

IF you continue to stretch an already lengthened you may be weakening your hamstrings and creating an “over stretched” muscle – that will likely become ineffective at stabilizing your pelvis.

IO pelvisTA pelvisppt

When your pelvis is rotated forward, your “core” and abdominal wall are stretched and not contracting well (think zone 3 and/or 4 in the previous image) and this can affect your overall movement (your core is where every movement begins) and it can affect your diaphragm/breathing (a post for another day!). The above images demonstrate how the core is involved. The top two pictures are of the Internal Obliques and Transverse Abdominis, and both attach to a substantial portion of your rib cage as well as the pelvis on either side. Together with the External Obliques (not pictured) they can help rotate your pelvis posteriorly (backwards). In the bottom image above, the middle figure is a posteriorly rotated pelvis. Knowing the attachments of these muscles, including the hamstrings, if contracted together, you can target the innominate and posteriorly rotated it.

The following posts will discuss exercise interventions – such as activating your muscles properly to control your pelvic range better – as well as how this poor pelvic positioning may influence other ailments you may have including low back pain, hip impingement, or knee pain.


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