It is my impression or she looks very strong in it pictures?
http://www.websitetoolbox.com/tool/view/mb/file?username=bettybicepsnet&id=32314
http://gallery.untouchablebritney.net/albums/userpics/normal_cadc227_5.jpg
http://img127.imagevenue.com/img.php?image=55606_97_122_838lo.jpg
http://www.britneyspears.bz/gallery/data/782/medium/654britneyspears-dot-bz_theonyxhoteltour-2004may30-0128.jpg


She does look used a hard workout too,looks gross and huge!