feeling it in the hip flexors???

[ms71069]

I'm doing the STS 6-month rotation and am on meso 1, my first week of discs 7, 8 & 9. My hip flexors are so sore - not painful sore, just that I'm really feeling them. I'm not new to Cathe and can't imagine why I'm having this problem with STS. I've actually cut back on my cardio/ab days (from three days to one) just to give them a little break!

Any thoughts/suggestions???
TIA!