Abadseal- Just curious, did you happen to round your lower back at the bottom of the RDL when the injury occurred?
No that's why this took me by such shock. I always use perfect form, 115's are not heavy for me for stiff leg as I was planning a 15 -20 rep burnout set, the only thing I can pin it on is perhaps going too deep. I usually stand on a 3' platform to get an extra deep stretch in the hams so maybe by doing this I took too much tension off the muscle and during the explosive portion of the rep it was just too much loading all at once????