It could have been deep in the bowels of English rugby's national stadium in Twickenham.

Instead, Phil Vickery was backstage at the Physical Culture Show in Hull, waiting for his moment - but this time as a bodybuilder.

However, the feeling was familiar.

"It reminded me of being in the changing room before the big game, your nerves - are you going to be sick, you're happy, you're not happy, I can do this, this is raw," he said, adding that just recalling that moment earlier this month makes his hair stand on end.

"That nervous energy and waiting and then, oh, it's just a horrific feeling. All the girls and boys can relate to that, because that's the same at whatever level of sport you play.

"I'm questioning myself, should I even be there? But then you go, actually, do you know what? I've done the work. I've done the graft."

What started as an ambition to get fit has ignited a passion for mental and physical fitness, and for Vickery being the best version of himself.

Then came a challenge from his friend Lee Powell and, with support from his physical trainer Dave Campbell, Vickery entering bodybuilding competitions at the age of 50. Posing to the strains of the familiar World Cup anthem World in Union.

"What it probably did for me is ignite that ex-pro rugby player in me of detail, discipline, turning up when it's dark and dingy and cold, competing, and we went from there," Vickery said.

"What I've fallen in love with, with the bodybuilding, it's a very singular, isolated sport, because it is you against you. It's not about anyone else.

"There is no out. You can't hide behind a keyboard. You are stood on stage. Your physique and what you look like is a direct reflection of your effort and what you have done, and that is quite scary."

The former Gloucester and Wasps prop won 73 caps for England, five more for the British and Irish Lions.

Victory at the 2003 Rugby World Cup in Australia was a sporting zenith in a career that includes being a businessman and a Celebrity MasterChef winner.

But personal struggles and a diagnosis for probable CTE (chronic traumatic encephalopathy), for which Vickery is part of a continuing litigation battle, means he has had to manage his mental health.

"We all deal with things differently," he said. "I think having the gym and having that space to be able to work is really important for my mental health, but also for my body physically, because it is broken, so I use it in that sense.

"I think the one thing I really struggled with when I finished playing is I trained to play and I couldn't find that reason to train afterwards.

"And although you should train for yourself or your wellbeing, it probably took a low point or something to actually trigger it.

"But, probably, the bodybuilding - or doing the show or doing the original transformation - I have to close the circle. You know, you have a plan, you make a plan, you implement it, you commit to it, see it through, and then it's over and it's done. And then you move on."

When Vickery took to the stage in Hull, he says he weighed about 99kg. More defined, but lighter than his playing days when he said his weight would range between 118kg and 135kg.

"[On stage] you look the best version of you that you could look, but you feel the worst. It's kind of a silly sport but it's amazing what the human body can do.

"Age, for me, doesn't bother me at all. I still think I'm 27. My body tells me different."

Training now involves three or four weight sessions a week, combined with daily walks (fasting cardio) and a protein-rich diet.

He hopes more shows will follow in the future.

"I can't do what I used to do and I think the battle for me, certainly when I finished [playing] and even to this day, is you cannot get back those feelings that you had when you used to do what you do," he said.

"I think doing things which can get you outside, test you physically and mentally, and put you in those uncomfortable positions. It's repurposing the skills that you've learned. You've just got to use them in a different way.

Vickery is known for his openness. He posts regularly on his social media channels about his health and fitness. But he's not comfortable with being labelled as an "influencer".

"We are all influencers," he said.

"I don't think everyone should go bodybuilding. My message is trying to be positive. Get out, do something, make a plan."

"I know I will never be a top bodybuilder. But it doesn't stop me, it doesn't stop me having a go and being the best version of me that I can be."