Maybe it isn't your muscles o SI. In my experience the SI is only the primary problem in about 10-15% of Sx in the posterior region and there is literature to support this. Muscles tend to be overworked or unbalanced ( side to side activation ) due more often in response to ...The yoga worked. Keep at it. Try cycling. I assume from the little info I have this will occur without incident but the proof is in the pudding as we say. Try deep water activity. Again, your spine is not responding well to the gravity factor on your spine. So this is an experiment to help Dx & Tx. Let me nknow what happens