A blast from the past! I ran in those back in the late 70s when I was young and fit. I liked them because they were very stretchy and flexible, never liked anything tight around the legs and I still don't.
No idea whether they're still available.
I recall the Ron Hill freedom shorts from the 70s, that's what we all wore. In hindsight they looked like bloody nappies, especially if they were a tad too big
Happy days.