Horse has tense muscles! how can i help her?

Like what that person said flex her then rub that area. i would also recommend to put either ice or a heating pack on her. ways to stretch her is make her put her head down as if she wa grazing or let her graze for a half an hour a day. lead her in a tight circle and make her neck bend both way it sounds cruel but i helps them relax she will most likely be soar so once again put an ice pack or heating pack on her