How quickly everyone assumes that a rambunctuous kid has a disorder (ADD, ADHD, etc.). If the child can focus enough to participate in structured activity such as gymnastics, swimming and others which requires concentration and following instruction I feel that when the kid is with you she is enjoying having every whim met by you. Do not bow so quickly to the demands every two minutes. Do you get to do what YOU want to do every 2 minutes? No, and neither should she.
Next time you go to the park you have a discussion before hand stating that if you walk to the park you will stay for 1 hour. If she is bored with frisbee playing, she can ride a swing, or go down a slide. Those can be the changing choices....not all this back and forth. Again, in the structured activities she follows orders as she should when being watched by you.
Just my 2 cents worth.