Hello Friends,



Here's a quick 2016 update from the science literature on your hamstrings...



Biomechanically speaking, tight hamstrings can affect the position of your pelvis, especially in forward bends. This can, in turn, affect your lumbar spine because tight hamstrings produce a pull on the ischial tuberosities and tilt your pelvis back (as shown below in figure 2).



Adjacent joints move in what is known as a “coupled” fashion. When the pelvis tilts back, the lumbar vertebrae flex forward. This means that if the hamstrings are tight and we bend forward in Uttanasana, more of the flexion comes from the lumbar spine. Conversely, when the hamstrings are flexible, the pelvis can tilt forward, allowing the forward bend to come from the hip joint, rather than the lumbar spine.



This interaction is known as spino-pelvic rhythm and is how the pelvis and lumbar spine move in relation to each other. Ideally, we want to have have a forward bend come predominantly from pelvic movement (pelvic dominance) rather than from the lumbar (lumbar dominance).



To this end, I wanted to share a couple of articles from the recent science literature relating to how tight hamstrings affect your pelvis and lumbar spine. The first one discusses spino-pelvic rhythm in relation to the hamstrings. These researchers investigated forward bends (essentially Uttanasana) in subjects with tight hamstrings vs flexible hams.



Figure 1 shows what happens with flexible hamstrings...





Figure 1: This illustrates how stretching the hamstrings releases the pull on the ischial tuberosities,

permitting the pelvis to tilt forward into anteversion. This is known as femoral pelvic rhythm.

Figure 2: Uttanasana: tight hamstring drawing pelvis into retroversion and

coupled movement of lumbar spine into flexion. This is lumbar pelvic rhythm.







Figure 3 illustrates the intervertebral discs bulging during lumbar flexion.



As the research demonstrates, stretching your hamstrings can help take the strain off of the ligaments and disks of the lumbar spine. Click here to read more on this subject. Click here to read about the role of the thoracolumbar fascia and the core muscles in protecting the lumbar. Click here for some cool information on gaining flexibility in your hamstrings as well as the myofascial connections between your hammies and your feet. (This shows how everything is connected...)

Figure 3: Lumbar spine in hyperflexion illustrating bulging discs.







Here's a quick review of the anatomy of your hamstrings...

The hamstrings comprise three separate muscles—the semimembranosus, semitendinosis, and biceps femoris. The biceps has a long and short head. The semimembranosus, semitendinosis, and long head of the biceps originate from the ischial tuberosities (sitting bones). The short head of the biceps originates from the back of the femur (thigh bone). The semimembranosus and semitendinosus insert on the inside of the tibia (lower leg). The two heads of the biceps join into one tendon that inserts onto the head of the fibula at the outside of the knee. The main action of the hamstrings is to flex the knee. Secondary actions include extending the hip and rotating the knee.





Thanks for stopping by. Click here to browse through our books for more key information on anatomy, biomechanics and physiology related to your yoga practice! See you later this week for a QuickQuiz on your hamstrings...

Namasté,

Ray Long, MD

What they found was...And in a subsequent article they concluded that:Yet another article reported that:(click on the references below to read the articles)