Early I published an article that explained how to prevent your hand from sliding off of your foot in Ardha Baddha Padma Pashimottasana.
Here is a brief excerpt
There is a problem when you try to hold on to your foot in this pose.
Alice came to me with a problem the other day. She is trying to hold on to her toe in Ardha Baddha Padma Pashimottanasana. Every time she gets a hold of her foot, her hand keeps sliding off. It is like her foot is really slippery. Her hand will not stay in place.
There is a problem when you try to hold on to your foot in this pose.Alice has worked her way through the first challenge with this pose. That challenge was to get the heel of her right leg in tight to her left hip with her ankle on top of the thigh and the knee of the right leg resting on the floor.
Alice is now working on the second challenge which is to reach around her back with her right arm and take a hold of the foot of her right leg. Gradually her shoulders have become more flexible and her hand has been slowly making progress behind her back towards the foot of her right leg. Just the other day Alice has started to take a hold of her foot.
Now Alice has a new problem. Every time she takes a hold of her big toe her hand gradually slides off of the foot. She can not keep her hand on her foot. Alice is looking for some help on how to keep a hold of her foot and stop her hand from sliding off.
Watch this video to find out how Alice solved her problem.
If you would like to watch it directly on Youtube you can use this link. http://www.youtube.com/watch?v=UCa0JE14JGw
