Friday, October 16, 2009

Proximal Hamstring Syndrome

I thought I would talk about a running injury that I have seen a lot of over this past summer and fall. There is a very specific type of hamstring injury that can occur in runners that, once present, can be hard to shake. The official diagnosis is 'Proximal Hamstring Syndrome' or 'High Hamstring Tendonitis' (or Tendinopathy), although, as we shall see, this injury has more to do with the pelvis as a whole rather than just being confined to the hamstrings.

This injury is fairly unique to runners, more often in woman, and especially in woman that have had kids.  (A joke in our office is that our number one patient is the running mom with butt pain.)  Runners with this injury typically feel the pain right up at the crease of the butt, somewhere near the ischial tuberosity (or the "sit bone"), which is the proximal attachment of the hamstrings. Sometimes the pain will radiate down further, leading runners to identify it as a hamstring injury. For other runners the pain is a little higher and will be labelled a gluteal or piriformis problem. When asked to point to where it hurts, the runner will often have a hard time locating the exact spot where the pain originates.

Other relevant structures in the area include the sacro-tuberous (ST) ligament, which merges with the hamstgrings at the ischial tuberosity, the gluteals, the sciatic nerve and the over-lying piriformis muscle. One interesting bit of anatomical trivia is that the hamstrings and ST ligament (along with the back muscles above and the calf muscles and even plantar fascia below) are literally connected by fascia (connective tissue), making them one continuous functional unit. A consequence of this is that tightness anywhere in that chain can pull on other parts of the chain.

The symptoms can range from chronic mild tightness in the area to more severe pain, especially during prolonged driving. In many cases it doesn't hurt to actually run, but more afterwards. The injury may relate to one specific muscle pull, especially during speed work, or just as commonly develops gradually over time with lesser intensities of running.

The tricky part of this injury is that it almost always represents a problem of the hip as a whole, and not just the hamstring. Classically the runner will have weak gluteals and/or tight hip flexors that tilt the pelvis, effectively pulling the ischial tuberosity upwards, pre-tensing the ST ligament and hamstrings. The picture below demonstrates a common postural dysfunction called "Lower Cross Syndrome", where in addition to the weak gluts and tight hip flexors the individual has weak abs and tight back muscles, contributing to a forward pelvic tilt.

My take on Proximal Hamstring Syndrome is that quite often it occurs in runners who demonstrate some or all aspects of the lower cross syndrome; maybe not enough to cause the normal accompanying symptom of lower back pain, but enough to distort the pelvis and preload the hamstrings and pelvic ligaments. Subsequently these structures then become more susceptible to injury. Starting from this basic template, there are different scenarios that can occur:

-The hamstring and/or ligaments can be overtly strained, or torn. This might happen with speed work, or with a forceful, unanticipated stretch, such as getting pulled forward while on water-skis.

-Just as commonly there isn't one specific tear but just continued tension and inflammation that causes adhesions (scar tissue) to become layed down along the upper hamstring and/ or the ST ligament itself. The longer this injury persists the more adhesions form.

-In some cases, the piriformis muscle also becomes involved, causing sciatic nerve irritation and more pronounced pain, sometimes further down the leg.

-I've even had some cases recently of runners where the only symptom was recurring calf muscle pulls. We were able to trace things back to the sciatic nerve involvement which was apparently causing subtle weakness of the calf, making it susceptible to strain.

Many runners self-manage this injury with hamstring stretching, foam roll work, and ice, but find that these remedies don't really make much long-term difference. As a matter of fact excessive hamstring stretching can actually make things feel worse, because you are just further aggravating a pre-tensed muscle. Rest may improve things short-term but the symptoms usually return when running resumes.

As far as treating this injury, most of the underlying factors must be addressed for true long-term resolution of the problem. A lot depends on how long the issue has been present. I've had cases when the runner seeks treatment soon after the pain has developed (before adhesions have developed) where simply releasing the hip flexor and having them strengthen the gluts resolved the problem. More commonly we have to add some cross-friction massage and Active Release Technique to the adhesed ligaments and hamstrings to fully alleviate the pain.

The biggest factor in preventing this type of injury (and many others) is to keep your core muscles strong, especially the gluts. This topic is worth its own blog, but essentially, for runners, I use the single-leg bridge as a benchmark. Being able to hold this position for 5-10 seconds solidly, without wobbling or hamstring spasm, indicates adequate strength for running. If you can't hold this position, do bridges with both legs on the ground, working your way to the single-leg version over time. Long story short, keeping your butt strong help will prevent one less pain in your butt!