I don't play play tennis but my kids do. At one of my daughter's tournaments a coach of another competitor complimented my daughter's power off her forehand but stated that her back swing was way too large and that would hinder her as she faced stronger players and faster paced balls. I purchased one of the coaching video apps for my iPad that can show slow motion video and was astounded by how large my daughter's back swing is. She brings her hand over her head, you can see her arm on the other side of her body when you face her and her contact point is at her hip so she follows through into her chest about 80% of the time. I was very upset with her coach for not recognizing this and making changes. So while I look for another coach I want to start to help her shorten that back swing. As I mentioned earlier I am not a tennis player but I can feed balls out of a basket. Any suggestions as to how to start? I'm considering tying shoestring to her wrists so that if she tries to make a huge loop she will be prevented from doing so from the limited length of the shoestring.