I put these laces into a pair of work boots that originally had laces that looked very workmanlike, but didn't stay tied very well. The new laces stayed tied while I did a few hours worth of yard work yesterday: mowed the lawn with a manual mower and did lots of foot movement.  I used a single bow, not a double. The laces are a bit stretchy, and I don't see any problem with that--it might even be an advantage in that it could contribute a bit of give to the laces as one's foot flexes.