He’s leapt from cliffs, clung to planes mid-takeoff and held his breath underwater for as long as professional freedivers. Now, at 62, Tom Cruise returns as Ethan Hunt for one final mission – and he’s still doing his own stunts.

With Mission: Impossible – The Final Reckoning, the saga reaches its high-stakes finale. But behind the scenes of death-defying spectacles lies a fascinating question: just how far can the human body be pushed – and trained – to pull off the seemingly impossible?

And at what cost? In filming the eight Mission: Impossible films, Cruise has suffered a broken ankle, cracked ribs and a torn shoulder.

Your mission, should you choose to accept it, is to consider the capabilities – and limits – of the human body in being able to achieve these awesome heights. How much is it possible to train to achieve the apparently impossible?

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Breathing underwater

In Mission: Impossible – Rogue Nation, Hunt navigates an underwater vault to recover a stolen ledger. Cruise wanted to film this all in one take and sought help from freediving instructors in order to hold his breath for the required time – over six minutes!

The average human can hold their breath for about 30 to 90 seconds. That’s without training. Although there’s an innate diving reflex built into the human body that allows it to temporarily adapt to immersion underwater.

The response is to lower the heart rate and redirect blood to the body’s core, essentially enabling it to lower its metabolic demand and preserve the function of the vital organs, like the brain and heart.

All well and good, but consider now the need to swim, as well as resist the pressure of the water pressing on the lungs. And also while fighting that desperate urge as a result of rising CO₂ to take a deep breath – which, underwater, would be catastrophic.

And if the diver’s oxygen levels fall too low, they might black out and lose consciousness. That’s why shallow water drowning is a real risk here.

That’s where freediving training comes into play. With practice, there are several ways you can increase the time you’re able to remain underwater. These include mastering breathing techniques to retain the maximum amount of air in the lungs. Sustained practice might also lead to increased oxygen storage capacity in the bloodstream.

This process takes months to years to attain and might lengthen the immersion time, on average, to around five minutes. What Cruise managed to achieve was nothing short of exceptional.

Free climbing – and that scene

Mission Impossible films often open with Ethan Hunt working his way up some impossibly sheer building or cliff face with the agility of a mountain goat. He appears to be free climbing without a harness, and at the start of Mission: Impossible 2, clinging on with just one hand. While Cruise used safety wires to secure himself, the climbing was 100% real.

Then, of course, how could we forget that scene? The one in the original Mission: Impossible – where he has to suspend all limbs, centimetres from the ground, to prevent himself from setting off the alarms.

Although Cruise hasn’t revealed his specific training regime for these stunts that I can see – performing any of these actions would require an exceptionally strong back and core.

The muscles of our backs keep the spine straight and upright. Some span the space between back and limb, such as latissimus dorsi, or “lats”. These sheets of muscle, prized by bodybuilders, are also particularly valuable to climbers – allowing you to perform a chin-up, or pull yourself up that rock face.

Besides this, many other muscles are needed for extreme climbing – those that enable a strong grip, allow for reaching and “push offs”, and maintain tension and hold. It’s no wonder climbing is considered one of the best whole-body workouts.

It’s no surprise that Cruise is known to have trained extensively for this. To understand even an element of the difficulty he may have faced, you could try adopting that vault heist pose, with your belly in contact with the floor, and see how long you can hold it. I won’t tell you how pitiful my own attempt was.

What a blast

Hunt has also escaped a fair few explosions in his time, from a helicopter in the Channel tunnel to a detonating fish tank in Prague. In Mission: Impossible 3, on the Chesapeake Bay Bridge, another helicopter launching a missile triggers an explosion that sends Hunt smashing into a car. Again, Cruise did it all himself, for the price of two cracked ribs.

Pyrotechnics were used for the explosion, but of course, they couldn’t be used to lift Cruise up and deposit him against the car. The solution? A series of wires were used to drag him sideways. Never has the direction “brace, brace” been so apt.

And just so you know, broken or bruised ribs are far from fun. Some describe them as one of the most painful injuries you can experience, since the simple acts of coughing, sneezing and merely breathing exacerbate the pain.

But Tom Cruise picks himself up yet again, dusts himself off and gets on with it. His motivation? He has reportedly claimed that he wants the audience to experience what it really feels to be in that moment. And what a good sport he is.

This article won’t self-destruct in five seconds.