Brooks Brothers is an American retail institution which sells “preppy” clothes for well-heeled white collar types who want even their dress-down-Friday rig of chinos and polo shirt to whisper Executive Class. An Edinburgh branch opened on upmarket George Street in 2007 for a then-record rent. Its arrival brought snide comments (from this paper among others) that it was well suited to a city whose denizens, unlike their brash neighbours in the metropolis to the west, shudder at the thought of sartorial ostentation and prefer instead a decidedly buttoned-down look.

I strayed over the threshold once or twice and was often the only person in there. Unsurprisingly, that branch of Brooks Brothers closed earlier this year, suggesting that while Edinburghers prefer the unostentatious, buttoned-down look, they're not prepared to pay a near-three-figure sum for a chambray shirt exhibiting those same qualities.

Perhaps there's another reason. You see the retailer which has replaced Brooks Brothers in that prime shopping site is Lululemon, proof I think that Edinburghers have fallen hook, line and sweat-wicking sinker for the trend sweeping the country: “athleisure”.

If you haven't come across this gloriously ugly portmanteau word, it describes an unholy mash-up of sportswear and its poor relation, leisurewear. Or stay-at-home-dad-wear as I call it.

Lululemon is at the top end of the athleisure market. It doesn't sell striped ties or sober suits in blue and black, but it does sell a dazzling array of hoodies, men's pants with names like Lock 'em Down and, for £52, an “all-sport V-neck with anti-stink properties” . Or a vest, in common parlance. Also worth noting is this: the yoga mat is now a bona fide fashion accessory, at least in Lululemon-land.

At the other end of the scale you'll find JD Sports. Probably with a glass of champagne in hand and a first class plane ticket to Mustique in the other: the company recently announced an 80% rise in profits and shares have doubled in price in the last year. So athleisure is everywhere, it seems, and is everywhere making money. Even in Edinburgh.

The corollary to the athleisure phenomenon, at least according to some doom-mongers, is the death of denim. Sales do seem to be down, but don't write the obituaries just yet. We went through the same thing in the 1990s when combat trousers were all the rage. Then along came The Strokes to usher in a decade of skinny jeans. The same thing will happen this time, I'm sure. We'll soon forget all about “cuffed pants”. If not, well, Wrangler is soon to introduce a pair of jeans with a tracksuit-style drawstring and I can't see why Levi's can't start producing denim yoga mats. I'd greet the sun on one of those.

What is certain is that, incrementally, athleisure will affect our workplaces. In the same way that jeans have become more or less acceptable in many offices, so will jazzed-up tracksuit bottoms and £100 sweatshirts.

For once I find myself ahead of the curve because as a home worker, every day is already athleisure day in my “office”. Hoodie? Check. Joggers? Check. Lock 'em Down pants? You betcha. Well, sorta.