Why do they recommend not doing some yoga positions while on your period?

Historically, in classical yoga, your period is believed to be a downward flow of energy.

Thus, inversion poses (upside down poses - example Plow pose, Shoulder stand, etc), are seen as blocking/contradicting that natural energy.

(technically, an inversion in yoga is any pose that puts your head lower than your heart -- by that definition, even Downward Facing Dog is an inversion.

You might be interested in following article on this topic at YogaJournal.com.

As author states at end, I think best advice is to learn and listen to what feels comfortable for your own body.

http://www.yogajournal.com/basics/831

Namaste',

dwb

I never heard about this ; and I do not know why ; you should not do yoga during your period ; but call a yoga teacher and she would answer your question

Who is "they"? So many "theys", who lack qualifications to make their recommendations, are unqualified to make "their" recommendations... Maybe you should consult your doctor about this matter...