“Running is the healthiest addiction you’ll ever have,” says Mr David Siik, an LA-based running coach at Equinox. “There is no such thing as a ‘StairMaster high’ or a ‘cross-trainer high’. But there is a ‘runner’s high’. And that’s because running floods your body with endorphins and then afterwards you get this amazing sense of peace and satisfaction that you can’t get anywhere else. Once a runner experiences it, they want more.”

This is exactly the kind of evangelical zeal you will have heard before from friends who run religiously. We all know those insufferably energetic people who clock up an easy 10 miles before breakfast and then smugly post their sweating selfies on social media as we try to shake off the excesses of the night before.

But watching this film of Mr Siik running around the canyons of Los Angeles, it’s hard not to feel inspired. “Honestly, I have clients who say running is better than therapy for giving them a sense of equilibrium,” he says.

Mr Siik, 34, grew up in Michigan and competed nationally as a middle-distance runner before moving into studying the science and biomechanics of the sport. Using the results of his research he created a work-out for Equinox called Precision Running.

Hang on a minute – running is simple. Surely this is one exercise that needs no further explanation. “You can always do something better,” Mr Siik counters. “My expertise is in correcting technique. Small bad habits can lead to big problems later on.”

This work-out is based around running on a treadmill – literally a synonym for mind-numbing repetition. That is until now. “Treadmills are so much better than they used to be, thanks to technology and innovation,” says Mr Siik. “People like me have taken it very seriously and created dynamic programmes that have a real plan so it’s not boring any more.”

The Siik technique adapts the well-known principles of HIIT – high-intensity interval training based on flat-out sprints followed by short recovery periods – and makes them safe for the runner. “HIIT is a heart-rate philosophy, not a running programme.” So he has developed BITE – balanced interval training experience – which minimises the risk of injury. “It hits that sweet spot between sprint training and distance training so you build both speed and endurance,” he says.

However this isn’t another new fitness fad. “I think society is sick of false promises. There’s always a crazy new work-out, a new trend that over-promises and under-delivers,” says Mr Siik. “Running is the oldest work-out in the world – we’ve been running since we were cavemen. It has always worked and it always will.”

But it only works if you’re prepared to put in the time and effort. “People want short cuts. They forget to actually put the work into the work-out,” he says. “When you do, running is the fastest and most natural way to see results.”

MR PORTER has teamed up with the health and fitness experts at Q by Equinox (the luxury gym’s online magazine) to produce a set of work-outs aimed at building a body that looks – and is – truly healthy. Watch this third video instalment to see Mr Siik demonstrate how to improve your running technique and build endurance while minimising your risk of injury.

Mr Siik’s quick fixes to avoid injury:

• Do the twist

Unless you have been prescribed running shoes with arch support, go for flexibility. You should be able to twist your shoe in your hands.

• Straighten up

Keep your arms parallel. If you swing your arms across your centreline (which is normally a sign of a weak core), the torsion can lead to lower back problems.

• Cut it five minutes short

Most running injuries are caused by a lack of stretching after your run. A combination of foam roller work and more traditional stretches for a minimum of five minutes will help ensure your muscles don’t tighten up.

• Watch your step

Some people over-stride, which is bad for the knees. Ideally you want to land your heel right underneath you, not in front of you.

• Slow down

Accelerating when running downhill is one of the worst things you can do for your knees. You have to slow down and strike with your heel first.

• Keep it regular

A key cause of injury is “binge exercising” – the guy who does nothing all week and then does one long run at the weekend. It’s much better for your body to do three runs of varying distances during the week rather than one long one.

• Stay in the middle

When on a treadmill, don’t run too close to the front of it. You’ll shorten your stride and box in your arm movement. Position yourself in the middle of the treadmill for a more natural form.

• Mix it up

Runners often pick up over-use injuries. Like a car, once you go over a certain mileage, things break down. The best way to prevent that is to mix it up and add in intervals, rather than just pound away clocking up the miles.

• Heel to toe

I believe in natural movement rather than trying to correct someone’s gait. That said, your body is designed to strike with your heel first – it’s a shock absorber. For slow-to-medium pace running, run with a nice heel-to-toe roll. For sprinting, run on the balls of your feet.

• Make a plan

Don’t just run aimlessly. Decide what you’re going to do in terms of distance, time, intervals, rest periods and stretching, and stick to it. You’ll get so much more out of it as a result.