HIIT – high intensity interval training – is one of the most effective ways to burn calories, tone muscles and increase your metabolic rate, so your body continues working after class for longer. They can be punishing but you’re doing the maximum amount of work in the minimum amount of time, so you can schedule in shorter workouts around the rest of your day. Almost every gym in town has a version of a HIIT workout on its class list but these are some of the best ones to try.

Check out our recs on the best barrespin, pilates, boxing, weights and yoga classes too.

Barry’s Bootcamp

Barry’s is the OG when it comes to treadmill and weights interval training. Loved by celebs and fitness fanatics from LA to London, you can burn up to 1000 calories in a class (believe us, they make you work HARD) in one of their signature red-tinted studios. Each day has a different focus, so you can target specific muscle groups or go in for a full body workout.

Bayswater, Belgravia, Bloomsbury, City of London, Soho, Canary Wharf & Shoreditch

f45 brixton


It’s absolutely huge in Australia and now F45 is a craze over here too because those who go swear by it. It’s a pretty simple concept; there are 31 varieties of 45-minute, high-intensity circuit workouts (mainly cardio or resistance based) with a different class on offer every day. The workouts are intense but effective, and there’s enough variation to keep you interested.

Various locations

Sweat IT

It’s very much does-what-it-says-on-the-tin with Sweat IT, as you will most definitely be sweating after one of their HIIT workouts. They combine treadmill runs and weights on their specialist rig, with sessions designed to target particular muscle groups. The Engine Room class is all about the lower body, Pillar Killer works your core, and Heart & Hustle focuses on the chest and back.

Covent Garden