Over the last 3 months I have bought a pair of Rockover shorts, a pair of Traverse tights and a pair of yoga pants for my wife. In each case they have a drawstring waist. The drawstring is a little different in that the ends are joined at the back inside the waistband rather than at the front. The join is made by sewing the ends inside a small tube of material. Unfortunately this join is not particularly strong. The drawstring on each of the items I mentioned has failed with what I would consider a very normal or even gentle tightening. To repair it requires unpicking the waistband and resewing, which is a bit of a bugger when it is the only pair of shorts in your pack and you are camped under Mt Hyperion

So if you are going to buy something like this it is probably worth running a couple of extra lines of stitches across the join at the back to avoid inconvenient interludes
bw