This article is from the Stretching FAQ, by Brad Appleton Brad_Appleton@ivhs.mot.com with numerous contributions by others.
For side splits, you can either have both kneecaps (and insteps) facing the
ceiling, which puts more of a stretch on the hamstrings, or you can have
both kneecaps (and insteps) face the front, which puts more of a stretch on
the inner-thigh (groin) muscle. The latter position puts more stress on the
knee joints and may cause pain in the knees for some people. If you perform
side splits with both kneecaps (and insteps) facing the front then you
*must* be sure to tilt your pelvis forward (push your buttocks to the rear)
or you may experience pain in your hip joints.
 
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