you need to break them in gently the first week or so you wear them ... not more than 3-4 hours at a time, yr muscles are just not used to being used that way.
my 2 cents: if u are spending big bucks on skechers, go the extra mile and get MBTs the original inspiration behind the shapeups...zappos sells them online, but rem the sizing in mbts are different..i was a size up from my regular size
as for the toning effect: i work out anyways, but these shoes helped me get rid of the soft look in my thighs, so i am pretty happy happy about that :)