Planks are a great whole body exercise! Here are a whole bunch of ways you can challenge yourself and take your workout up a notch starting with a standard plank.
Tag: Pilates
Total Leg Workout!
http://www.youtube.com/watch?v=jrMNcyeddOM&feature=g-upl
Looking to tone up those legs? Try this at home!
12South Pilates & Personal Training 