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I have been doing yoga pretty regularly lately and have advanced in my core strengthening postures. My core muscles are getting fairly strong. I am able to stay in the yoga headstand for as long as I want, or I was able to. Lately, a strange thing has been happening while I do my headstand (and shoulder stand, although not as much) postures. My legs and torso seem to having a life of their own and are twisting around in all sorts of new and sometimes frightening positions. I could stop it but I know what is going on so I don't want to. My legs most frequently want to bend back over my head, which disrupts my balance, so I have to stick my chest out to compensate and end up really bent over backwards. I can stay like this for quite some time, but eventually my arms get tired of holding me in a balance and I fall out. I look something like this, except with my head still on the ground. I need someone to spot me so I don't break my neck, but no one is ever around. I also bend side to side. It is probably quite scary to watch my body contort to all these positions seemingly of its own violation.