Hamstring Influence on an Anterior Pelvic Tilt

Jason’s new blog explains the Hamstrings Influence on an Anterior Pelvic Tilt… (Jan 2013)

Often times I hear my patients complain about how tight they are, more specifically how tight their hamstrings are.  Furthermore these individuals often times struggle to bend over to touch their toes, and it seems that everyone’s advice is to stretch those tight hamstrings! Most often individuals think their hamstrings need to be stretched because they have a sensation of tightness.  However, there are two types of tightness; mechanical and neurological. It is important to differentiate between the two and understand why stretching the hamstrings oftentimes won’t fix the problem, and why there may be a need to strengthen the hamstrings, as they play an important role in stabilizing and positioning the pelvis.

Mechanical tightness occurs when a muscle is positioned in a constant shortened state, which causes the muscle to become physically shorter and increasingly tight over time. Neurological tightness, on the other hand, occurs from a muscle being consistently elongated in a lengthened position for an extended period of time. When a muscle is placed in a lengthened position, it receives additional signals from the brain, which is thought to be a protective response from the body to prevent the muscle from being stretched too far and thus these increased neural signals is what creates the sensation of tightness.

In April 2012 I blogged about the anterior pelvic tilt.  The anterior pelvic tilt occurs when the pelvis tilts toward the front of the body.  From a mechanical/structural component, an anterior pelvic tilt causes some muscles to be tight and others to be lengthened.  More specifically, the muscles in the front of the pelvis become shortened because they are positioned in a shortened state and the muscles in the back of the pelvis, hamstrings, become lengthened due the pelvis being tipped forward.  With time, this leads to the neurological tightness which is often misunderstood.  The tightness an individual feels is one’s body trying to protect the individual from overstretching. Therefore, stretching more doesn’t solve anything. In fact, it may only worsen the problem. Instead there is a need to focus on strengthening the hamstrings to help counteract this anterior pelvic tilt and restore proper pelvic position.  Furthermore, the lower back is in a state of hyperlordosis and appears to be tight due the fact that the back muscles are overactive in attempt to bring the upper body back into an upright position.

From a clinical standpoint, “tight” hamstrings do not necessarily mean short hamstrings, and therefore does not mean stretching is the right thing to do.  Often times an individual will have a limited straight leg raise (a common objective test used during movement screens which consists of lying on one’s back with both legs straight, and then the examiner actively raises one leg as far as they can) due to the sensation of tightness of the hamstrings.  A common misconception is that the hamstrings appear to be short and tight and need to be stretched. On the contrary, the hamstrings are actually lengthened and tense secondary to the pelvis falling forward and need to be strengthened to return the pelvis to a more neutral/optimal position. Often times patients with low back pain are often told to stretch their hamstrings to relieve the sensation of tightness/discomfort. In response to stretching of the hamstrings, the pelvis may tilt even further forward and the lower back muscles may become tighter to keep the body upright.  It is important to think less about an individual muscle or muscle group as it relates to the sensation of tightness, and instead think in terms of the position in which the muscle is held!

Let’s take a closer look at the straight leg raise. Think back to the anterior pelvic tilt which places our lower back in an arched position, or what clinicians call lumbar lordosis.  When the clinician lifts the leg for the straight leg raise, the hamstring becomes taut at an earlier point then it should because the muscle is already pre-lengthened due to the position of the pelvis (anterior pelvic tilt).  In other words, the leg won’t go as far because it’s already being stretched before it even moves.  Positionally, the tightness may be felt in the hamstrings but the hamstring is not shortened—it is lengthened! It may be related instead to the position of the pelvis or anterior pelvic tilt.

Although many individuals may claim they cannot touch their toes due to their hamstrings feeling “tight”, stretching these already lengthened hamstrings may bring about potential injuries to the pelvis, lower back, and knee.  Instead, one needs to focus on strengthening the hamstrings to reposition the pelvis to a more neutral position in order to restore proper mechanics around the pelvic girdle.  The position of the pelvis plays a vital role in how the spine above it and the femur (thigh bone) below it will function.  It would be fair to say that an abnormal position of a structure will result in an abnormal movement of that respected structure.