Absolutely not!  The only requirement for practicing yoga is the ability to breathe.  It’s a common misconception that yoga requires people to twist themselves into pretzels.  But while advanced postures like headstand may be part of the yoga practice for some people, they are by no means required.  Yoga poses should be selected to fit each individual’s abilities and needs.  For many people, yoga practice involves easy, yet powerful, meditative movements that anyone can do.