For many people, the main concern in a yoga class is whether they are breathing correctly or their legs are aligned. But for others, there are lingering doubts about whether they should be there at all, or whether they are betraying their religion.
Farida Hamza, a Muslim woman living in the US (pictured above), had been doing yoga for two or three years when she decided she wanted to teach it.
"When I told my family and a few friends, they did not react positively," she recalls. "They were very confused as to why I wanted to do it - that it might be going against Islam."
Their suspicions about yoga are shared by many Muslims, Christians and Jews around the world and relate to yoga's history as an ancient spiritual practice with connections to Hinduism and Buddhism.
Last year, a yoga class was banned from a church hall in the UK. "Yoga is a Hindu spiritual exercise," said the priest, Father John Chandler
. "Being a Catholic church we have to promote the gospel, and that's what we use our premises for." Anglican churches in the UK have taken similar decisions at one time or another. In the US, prominent pastors have called yoga "demonic"