I don't just use these to work out in... I use them all the time because I was developing heel spurs and these helped me correct the problem by helping me correct my gait.  The ultra thin and flexible soles make it so that you feel EVERYTHING you're doing when you walk in them.  Every little bad habit you have you will feel because you feel the way your foot hits the ground.  I always knew I had a problem with foot supination and that supinators tend to get heel spurs. (Turning the foot out while walking denies the ligaments normal stretch.  The ligament tightens and a spur develops over time.)  But I could never seem to stop the habit of supinating that I had all my life.  These shoes had me feeling everything so that every step was a reminder of my bad habit and that constant reminder was just what i needed to change my habit.  After only about 6 weeks of walking in them (first only while in the house and then worked up to outside) the habit was permanently changed and my foot pain was gone.  And after almost a year my pediatrist compared x-rays and said that my spurs rate of growth had stopped.  I still wear them regularly to make sure the habit doesn't come back.  What I hate is how ugly & weird fivefingers look.  I sure get looks walking in these around the city.  I wish they made a pair where the toe seperation was only on the INSIDE of the shoe and the outside looked like just a regular ballet slipper.  Yes I know there are other barefoot brands that have a thin sole without the toe separation, but the soles of those other brands always feel thicker & less flexible to me than the vibrams which I think are the truest barefoot shoe because the sole is truly thin.  I really hope Vibrams start to make a shoe that doesn't have the 5 fingers so that I can wear them around the office and still enjoy the super thin flexible soles they have that no one else seems to.