Anatomy Blog – A sad story about Hamstring

Anatomy Blog – A sad story about Hamstring
I always knew that my left leg hamstring is tighter than the right because I could feel the tightness whenever doing Paschimotanasana, Janu Sirsasana or just a forward bending Uttanasana, comparing to the right side. So I started to stretch more of the left leg hamstring in order to improve the flexibility so as to perform the “perfect” asanas. After a period of time, I started to feel the strain of the left hamstring more and more, which at first I thought was some “good pain”, that could probably mean that I was making progress and by the time it gets to the same flexibility as the right side, the pain will dissipate. So I thought…..
Unfortunately the strain seemed to became perpetual and what’s worse was that I started to feel a nagging pain at my left sit bone and sometimes also at the back of the thigh right above the knee. I couldn’t even do a proper Uttanasana without bending the left knee slightly because the pain was rather unbearable should I fully stretch it. I guessed it could be because of muscles tightness and went for many massage sessions, felt a little bit better right after but it came back again when I attempted the forward bending or whichever pose that requires stretching of the hamstring.
During the study of Anatomy of muscles and googling “hamstring muscle pain” and “strained/pulled hamstring muscle” on line, I found out that the pain I’ve experiencing is not just muscle pain/soreness that simple. It is probably a partial tear in one of the two short tendons that connect the hamstring muscles to the sitting bone. It may be right at the bone, at mid-tendon, or at the junction where the tendon merges into the muscle.
The anatomy of this injury is quite simple. The hamstring muscles consist of three major muscles, bicep femoris, semitendinosus and semimembranosus. The upper end of each of them attaches to the sit bone (ischial tuberosity). Two of the hamstrings (semitendinosus and biceps femoris) share a single, short tendon that joins them to the sitting bone. The bicep femoris has an addition head origins from the back of the femur. The third (semimembranosus) has its own short tendon. The lower ends of all three hamstrings attach just below the knee on the two lower leg bones, the tibia and fibula.
When these muscles contract, they bend the knee and extend the hip joint. To stretch them effectively, one must simultaneously straighten the knee and flex the hip joint. This is just what happens in Uttanasana and other straight-legged forward bends: the knee straightens and the hip joint flexes. This moves the sit bone away from the back of the knee and lengthens the hamstring muscles. Hamstrings are strong muscles, so it can take a lot of force to stretch them. However when the force is more than the tendon can bear, the tendon partially tears at or near the sit bone.
For my case, the torn tendons didn’t happen suddenly. Instead, it is “death by a thousand cuts”: each tiny rip in the tendon is relatively minor by itself, but because it does not fully heal, repeated injuries accumulate over time. When the first tear happened, I mistaken it as muscle tightness and I was experiencing the soreness as a result. Immediately after the injury—however tiny it is—adhesive scar tissue forms. While this scar tissue is meant to protect the tendon as it heals, quite often the scar tissue hampers the healing process, preventing a full recovery. Scar tissue limits circulation and stiffens the tendon, leaving it more vulnerable.
Being too eager to achieve my goal of getting the full flexibility of the hamstring, I’ve dismissed each little injury after enduring some soreness and pain (I probably have a high tolerance for pain, fortunately or unfortunately, *sigh*), I was trying to stretch my way out of the injury too soon, too hard, and too often. This not only slowed the healing process, it also produced excessive scar tissue. Scars don’t stretch well, so later stretching in the same area can put excessive strain on the intact tendon fibers surrounding the scar, causing additional injury. This, in turn, produces more scar tissue, leading to a vicious cycle of progressively worsening injury.
I’ve learnt that tendons have a much poorer blood supply than muscles, so when you tear them, they heal much more slowly. Such injury to the tendons can take six months to a year to stop hurting—and even then it does not mean that it has fully healed. The attachment remains far more susceptible to re-injury…… Arghhhh… Arghhh… Arghhh…
I suppose the lesson learnt from this is to really have a thorough understanding how the muscles work in each asana and how each asana affects specific muscles/muscle groups, with the awareness of the synergists and the antagonists at the same time, so as to engage the correct muscles to either strengthen or stretch them during yoga practices.
How I wish I had learnt the functional anatomy in yoga much earlier, I wouldn’t have had this “pain in the butt” LITERALLY! for so long and it’s gonna be there for quite some time… *triple sigh*
Zoe Z 27th Apr 2015

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