What's it like to train with a navy SEAL?

As I walk through the gym door, I hear my interview subject before I see him. Jeff Nichols has that booming, unapologetic American trainer-type voice that announces itself like a Tannoy.

He is no less imposing on sight, and pretty much exactly what I expected a Sea, Air and Land Force trainer (in US military parlance, a SEAL) to look like.

The tattooed titan has been flown in to help Australian sportswear brand 2XU celebrate its 10th birthday. Scenes from Stanley Kubrick's Full Metal Jacket flash before me, and I gulp hard.

I'm here to be put through my paces in the same way Nichols would train a SEAL – or his athletes, as he calls them.

"I'm not an athlete," I clarify nervously. "We're ALL athletes", Nichols shoots back, "we just gotta bring it out. That's the whole point." Yikes.

Training day

This 90-minute session will, mercifully, be a highly-truncated version of the notorious six-month long selection sessions that Nichols spent 11 years administering for the US Government.

They involved sleep deprivation, hypothermia, and in some cases, death, Nichols tells me, before nonchalantly adding: "We gotta find the best, and that's the only way. Some people just can't take it."

Such intensity prepares the recruits for the unforgiving environment of places such as Afghanistan, where Nichols himself once battled hypothermia-inducing temperatures and an entire week's sleep deprivation, plus an ankle injury from a "parachute malfunction".

Once a SEAL has been selected, they "go back to square one" and do some of the training he'll show me today – less about pure intensity, which "just causes the body to stress; not good", and more about honing the "efficiency" with which the body can train.

Pump my guns

Meeting Nichols – ginger, blue-eyed and bearded – I realise I'm looking at an ultra-bulked up version of myself (I'm also a 'ranga'). It's like one of those smart-phone apps; instead of "fat my face", it's "pump my guns" and I see what I could look like if I basically lived in my gym.

He hands me a pair of the sponsor's skin-tight training leggings that accentuate everything (and I mean everything) but apparently offer excellent compression, which is said to encourage better blood flow back to the heart, decrease fatigue and injury risk, reduce DOMS (delayed onset muscle soreness) and accelerate recovery.

Nichols assesses me very quickly. After making me hop like a schoolkid, sideways walk like a crab and fast backwards-walk like an intoxicated fool, Nichols delivers his analysis: more prone to injury on the left side, and especially the shoulder. He's spot-on. He shows me how my left shoulder protrudes slightly more than my right: a bodily blemish of which I'd been blissfully ignorant.

It's clear he can sort the wheat from the chaff very quickly, and I'm about to discover which I'd probably be.

SEAL squad

What follows is an 80-kilogram sled push (exhausting), some kettle bell squats (tolerable) and an exercise where I have to slam two ropes down like I'm irate with them (strangely cathartic.) We chat as we train. Correction: Jeff chats. I'm too knackered. He talks a lot of science and I nod as though I understand more than 20 per cent of it (I don't).

When I get my breath back, I clarify a few points. If you want to train as hard as a SEAL, two things are essential above everything: the brain, and your recovery. The actual physical training is almost just a side dish. "It's all brain," he tells me.

The amount of time you take to recover between sets involves a maths formula so precise and complex, Newton would be zoning out, but take time to recover between sets. Between 90 seconds and two minutes is standard.

Recovery goes beyond this, though – getting enough sleep is mandatory. Between eight and nine hours is a must, Nichols says, and I instinctively lie about last night's six-hour snooze when he asks. I just want to impress him. I think it's working. He has stopped booming at me like he resents me, his commands now a lot closer to room volume.

Staying hydrated

Hydration is another top tip to train smarter. Most people are dehydrated, Nichols asserts, and we should all double the amount of water we drink. I glug some down straight away in a further desperate bid to win his approval. He ignores the gesture and hands me some 2XU compression socks.

They feel like socks that have been in the tumble dryer too long, but that's about gaining the recovery benefits of compression. Apparently they are superb for long-haul flights: "If there's only one thing you take from me bombarding you with all this information, just wear those socks on a flight. You'll feel twice as good when you disembark," Nichols says.

I show him that I've underlined this twice in my notebook, to demonstrate that I've attentively prioritised his tip. He seems content.

On that high note, we're done. Do I have what it takes to be a SEAL, I wonder aloud. I'll never truly know, as Jeff has already moved on to train another visiting client. His mini-me makes a tired but proud exit.

Jeff Nichols' top tips for training like a SEAL

1) Double the amount of water you drink

2) Mind over matter: treat exercise as meditative and neurological, rather than just physical

3) Wear compression garments like the tights and socks from 2XU

4) Do your toughest exercise first

5) Get in the routine of sleeping 8–9 hours every night