Ahead of the actor’s new documentary <i>Fighter</i>, MR PORTER finds out what it takes to be a kickboxer.

In October 2015, at a charity kickboxing night at York Hall in Bethnal Green, east London, a rumour started to spread. Mr Idris Elba, better known as Stringer Bell, or Luther, was in the building, and was preparing to walk out for three rounds of Thai fighting with a professional kickboxer. Mr Elba, it turned out, had been training for the fight for the past year, in Cuba, Japan, South Africa and Thailand. A Discovery Channel documentary tracking his training – Idris Elba: Fighter – premieres tomorrow. As a father of two, and with two high-budget feature films in production, Mr Elba had to fit his regime around a busy professional lifestyle, waking up at 4.30am to train before 12-hour shifts on set.

Boxing and kickboxing are becoming popular ways for busy people to get fit, and specialist fighting gyms are springing up across the UK. For fast, intensive exercise, few sports are as social, as adrenaline-inducing or as addictive. MR PORTER talked to Mr Elba himself, as well as a former kickboxing world champion, a former Thai boxing world champion and a former British kickboxing champion, all now London-based coaches, to get an expert’s guide on how to train as a fighter while living a full-on, urban lifestyle.

Kickboxing is a highly technical sport, and it’s hard on your body. If you get it wrong, or have a bad attitude, you can get hurt. So how do you learn quickly?

“My ego was definitely deflated many, many, many times,” says Mr Elba. “I definitely took a beating. I was training with guys that were smaller than me. I was being beaten down by people that my ego thought I could handle – and I couldn’t.”

“A lot of young students want to run before they can walk,” says Mr Keiran Keddle, Mr Elba’s coach and a three-time Thai boxing world champion who now runs Double K Gym in Bromley, south-east London. “But they always get found out. So don’t overindulge. Take your time, and always listen to your coaches.”

“There’s a science to fighting,” says Mr Stuart Lawson, a former world champion kickboxer and co-founder of Paragon Gym in Shoreditch. “It’s not just about being tough. To be a student of martial arts, you need leave your ego at the door and train in a safe environment.”

“Make the most of your time in the gym,” says Mr Mark Walker, a former British kickboxing champion and founder of MAW Boxing. “Enjoy the journey. If you do that, everything else will fall into place.”

How much training should a fighter do? When are the optimum times to train and for how long? And how intensive should these sessions be?

“To be at your best, and to avoid injuries, you need to ensure you get enough rest,” says Mr Walker. “If you try and go 100 per cent, all the time, you will burn out, so listen to your body.”

“I would wake up for a training session at five in the morning,” says Mr Elba says. “I would train for about an hour – burpees, push-ups, sit-ups, and then some pad work – then I’d go and start my day on set. By the evening, I was knackered.”

“For someone with a busy life who wants to fight, I would suggest six to eight one-hour sessions a week,” says Mr Lawson. “If you can, train twice in a day – once in the morning and once in the afternoon or evening. It’s important to take a day off every three days to let your body rest.”

Fighting requires a mix of strength and flexibility, stamina, endurance and technique. How much time should be spent on each area, and how should you balance it with other activities?

“I’m very old school,” says Mr Keddle. “I prefer pads, sparring and bag work. And then long runs, skipping and sprint work in the student’s own time. Swimming and yoga are good for flexibility and to take your mind away from it all.”

“The further away from a fight, the more strength and conditioning work you should do,” says Mr Walker. “The closer you get, the more you want to focus on skill-specific work. “Climbing works well, because of the weight you place on your arms and legs. Yoga works well for suppleness.”

“I would spend time in a sauna after my evening sessions, and I would get a massage, because your muscles can get very fatigued,” says Mr Elba. “They made a big difference.”

A fighter’s diet is almost as important as their training schedule. But there are different schools of thought on what one should eat when preparing to fight, particularly if you need to shed weight.

“A boxing match between two fighters of the same strength and talent can come down to who has the better diet,” says Mr Walker. “But diet is a highly individual thing, and everyone has their own advice.”

Says Mr Lawson: “If you need to lose weight for a fight, make sure you do it slowly. Start at least eight weeks before competing so your body can adjust without being put under unnecessary pressure. Aim to drop by about 500 or 600 calories a day, rather than embarking on a massive starvation quest.”

“There’s a myth that we need loads of carbs to train and have energy,” says Mr Keddle, “but a lot of it is in the mind. With a good diet of white meats, fish and vegetables, you will have enough energy to train.”

Idris Elba: Fighter premieres at 10pm on 17 January on the Discovery Channel