As Mauricio Pochettino prepares to take charge at Manchester United, former Tottenham Hotspur right-back Kyle Walker has offered a vivid glimpse into the physical demands that await the club's players — centred on a running drill so punishing that only one player ever finished it.

Speaking on The Overlap, a show produced in partnership with Sky Bet, Walker recalled the infamous 'Gacon' test that Pochettino deployed throughout his time managing Spurs, and described Dele Alli as the sole player he witnessed see it through to the end.

What is the Gacon test?

"We had the famous thing called the Gacon — whoever played for Tottenham will know the Gacon," Walker explained. "It starts at 145 metres and you have 45-seconds to get there, you then walk up five metres [to another cone] and have to run back. It's a continuous thing and there were 16 or 17 cones."

"The only person that I've ever seen complete it was Dele Alli — he was an animal at running."

Alli's exceptional endurance was central to Pochettino's system at White Hart Lane during the mid-to-late 2010s. Operating as an aggressive attacking midfielder behind Harry Kane, Alli consistently ranked among the highest distance-coverers on the pitch, driving Tottenham's counter-press and fuelling back-to-back Premier League title challenges in 2016 and 2017.

Walker's culture shock at Manchester City

The relentless running culture Pochettino instilled at Spurs stood in stark contrast to what Walker encountered after his £50 million move to Manchester City in 2017. Under Pep Guardiola, pre-season training revolved almost entirely around possession drills, a world away from the lung-busting fitness work of his Tottenham days.

"I remember getting off in the pre-season [at Manchester City] and you've got Kun Agüero who's just balling around training — bad trainer, bad trainer, but he turned it on in the game," Walker said. "I got back to my hotel room after and speaking to my dad saying, 'I think I've made a mistake here.'"

Walker described going from a Pochettino team built on relentless running and high pressing to a Guardiola side that did "hardly any running in pre-season because Pep doesn't like running — we did a little bit but it was mainly with the ball."

Those early doubts soon dissolved. Guardiola's ball-dominant philosophy delivered multiple Premier League titles and the UEFA Champions League during Walker's time at the Etihad Stadium.

What United players can expect

With Pochettino now set to return to English football, Walker's account is a clear signal of the intensity the Argentine will demand from his Manchester United squad from the opening session. Pochettino's first match in charge is expected to be United's trip to Anfield to face Liverpool FC on 22 November.