Every were I go folks are talking about “toning” shoes. Do they or don’t they really firm you while your walking? Vibrant Nation says probably not. That muscle strain your feeling is “due to localized muscle soreness after wearing them the first few times. Researchers suggest that this feeling is due to the shoe’s unstable sole design, which causes wearers to use slightly different muscles to maintain balance than they would while wearing traditional shoes (I’m not sure that’s a good thing long term).” If they feel good keep wearing them but don’t expect to get firmed up while your wearing them unless your taking a walk in them!