Discussion: What is a Nails run?

Is it an newfangled version of a vintage circa 2001 'Sprot'?

It's where you run through town at rush hour "accidentally" bumping in to commuters shouting "bah-humbug" and "Chuff off ya dozy bleeder".

Ah, that makes sense now. I thought it might be where you set off way too fast at the start and then quit halfway through the run.

Camel's explanation is better but it is a 4 miles tempo run. It is called a Nails run because this is his steady running pace - well until he got carried away with the beers at least.

A better Nails session would be to get into an altercation in the street with a driver and then have to sprint away; hiding behind bins would be your recovery.