Causes for the injury?

In retrospect, I’m trying to figure it out . . . three possible causes or aggravators of the injury

  1. On the referenced, 13 mile trail around the time the pain began, I began to notice a left ‘hip’ or buttock pain.  I did experience a “typical stumble and fall” and happens from time to time on a trail run and yes it was a totally flat area over a 1″ rock.  Involuntary movements during falls can be damaging and perhaps the eccentric HS contraction of catching the left leg on a fall did the damage.
  2. I began around this time doing some Iyengar Yoga, which I had done before but quit for about a year.  This is a slow and purposeful yoga style designed to enhance flexibility.  Attention of hamstrings is a large part of each class.  Have been doing the classes about twice weekly since injury and overall seems to feel a bit better after a class however, after a week on vacatin with no yoga, I had a very good couple of days then a not0-so-good day following return to yoga.  I may discontinue yoga for a bit or severely limit the poses to those not involving hamstrings.
  3. I began around this time to do some work on core musculature for improved running using this book, Foundation, redifine your core . . .  While it seems to be focused on conquering back pain, it does emphasize some excellent drills for posterior core and improved posture.  On one particular drill, lying prone, legs and arms extended and off the floor in the ‘superman’ pose I particularly noticed pain in the L hamstring . . . not saying this was the cause . . . it was probably just aggravating the HS as this pose is most definitely an activator of the biarticular HS muscle.  I quit doing the drills early on pending evaluation of my injury.