Unveiling London’s Best-Kept Fitness Secret: The Underground Gym Revolution

Every day, away from prying eyes, clientele ranging from CEOs and Hollywood stars to billionaires and Saudi princesses, are put through their paces in underground gyms scattered across the capital. 

In these under-the-radar facilities, something remarkable is happening. The results achieved by an in-the-know client group surpasses anything you’ll see anywhere else. It’s this success, combined with the unassuming setting, that makes these spaces unique. 

You may well have walked past Ultimate Performance’s (U.P.) five London gyms – particularly if you’ve visited some of London’s most affluent locations in Mayfair, Kensington, and the City – but never realised they were right under your nose.

For example, U.P.’s underground Mayfair gym is situated just yards from Hyde Park and within touching distance of the Aston Martin garage. Yet, you could be standing outside and not even realise it. In London’s bustling and vibrant West End, U.P.’s basement Kensington gym is discreetly – almost invisibly – located between two shops. Despite being situated in bustling and trendy parts of the city, the gyms are built to maintain a sense of privacy and exclusivity that sets them apart from other fitness establishments in the area.

As the world’s most successful global personal training business, Ultimate Performance operates a network of gyms globally. The company has transformed the lives of 28,000 clients since its inception in London. Whether you’re in LA, Dubai, or Sydney, U.P. offers the same top-notch training and guidance provided to A-list celebrity clients like Olivia Coleman, Glenn Powell, and Dustin Hoffman. In 2022 alone, U.P. clients collectively lost 31,000 kilograms.

And the minute you step inside a U.P. gym, you instantly realise these are not your run-of-the-mill commercial gyms, but something else entirely.

There are no private saunas or fancy Pilates sessions here. There are no steam rooms, flashing neon lights or candle-lit massage booths. So, it may seem incongruous that U.P. gyms attract such high-profile and wealthy clientele when the gyms themselves do not immediately scream first-class luxury.

And yet, people are prepared to wait for months to gain access to these exclusive gyms.

So, what makes Hollywood stars and London’s elite flock to Ultimate Performance? How does a personal training business with gyms so hidden, become the most sought-after and successful PT business in the world?

One word: results. The second you walk into one of these best-kept-secret gyms, you will be instantly greeted by a results wall – a jaw-dropping display of the incredible transformations that have established Ultimate Performance as the world’s pre-eminent personal training business.

Ultimate Performance trainers are a different breed from the rest of the industry. Everything U.P. trainers do is solely focused on getting the best possible results for their clients in the shortest timeframe possible. It’s why the company has a ‘maximum results, minimum time’ mantra, and it’s why the waiting lists are so long, despite the premium cost of working with a U.P. trainer. Rather than spend millions on trendy advertising campaigns like other gym businesses, the results of U.P. clients do the talking.

And the secret behind the world’s most impressive transformations? At U.P., clients don’t get just one trainer, they get access to an entire team. The ecosystem at U.P. is the backbone of the training system that sets them apart.

At Ultimate Performance, you pay for a fully managed lifestyle service that goes beyond traditional gym training, with a dedicated team working behind the scenes to ensure the best possible results. They offer an ecosystem built to maximise your return on investment.

Ultimate Performance Founder, and Global CEO, Nick Mitchell said: “That is why we get results so consistently that no one else in the industry can touch.

“You’re paying for the best gym floor service, in the best gym environment, and critically, you’re paying for the accountability and comfort of a team of elite personal trainers. No stone is left unturned, and no process is left to the whim of an individual trainer.

“On top of this, the standard approach where a trainer says ‘hello’ and ‘goodbye’ to their client at the gym door is an anathema to us.”

“If a trainer doesn’t get good results, they won’t last long in my company. That’s why we are so different. We are all about results.”

You can find U.P.’s London gyms at these locations:

  1. Canary Wharf – 10 George St, London, E14 9QG
  2. St Pauls – 31-33 Foster Lane, London, EC2V 6HD
  3. London Kensington – 62-64 Kensington High St, London, W8 4PE
  4. London City – 44-48 Paul Street, London, EC2A 4LB
  5. Mayfair – 2 Park Street, Mayfair, London, W1K 2XA

For more information or to make an enquiry, please visit the Ultimate Performance website.


Ultimate Performance (U.P.) was founded in 2009 in London by world-leading personal trainer Nick Mitchell.

U.P. have forged a reputation as the world’s foremost body transformation experts delivering exceptional client results under the mantra ‘maximum results, minimum time’.

The business has grown to become the world’s only truly international personal training company, with 21 private personal training facilities across the globe, including London, Liverpool, Leeds, Manchester, Cheshire, Los Angeles, Hong Kong, Dubai, Singapore, Sydney, Amsterdam and Mumbai.

Now, U.P. boasts a team of more than 300 elite personal trainers across the global business, working with thousands of successful body transformation clients.

Men’s Fitness Magazine describes UP as: ‘The Goldman Sachs, Real Madrid and Apple of Personal Training. They’re that far ahead of the field.’

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