Dr Charles Eugster, retired British dentist took up bodybuilding 10 years ago and, now living in Zurich, is thought to be the oldest bodybuilder in the world. He also rows and runs.

He’s adamant that he’s healthier and fitter now than he was in his 40s, telling the Daily Mail: “My ex-wife recently sent me a picture of me in my 40s and it is disgusting.

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"I was a really horrible, self-satisfied, blobby, fat person. As a young man I’d always been quite sporty, but I’d just let that side of things slip away… This idea that you have to wither as soon as you turn 60 — nonsense!”

And Dr Eugster isn’t the only strong older man. In 2013, Japanese climber Yuichiro Miura became the oldest person to reach the summit of Everest, at the age of 80. In June, 55-year-old US Navy veteran Rodney Hahn broke the world record for the most pull-ups in 24 hours.

So why are some men seemingly so fit over 50, is old-man strength a real thing?

Two professors from the University of Nottingham’s faculty of medicine, Daniel Wilkinson and Philip Atherton, recently wrote about the phenomenon for The Conversation.

They reckon the reason men like Eugster, Hahn and Miura have been able to achieve such feats of endurance is not due to any kind of hormone-related burst of energy in later life.

“Reports of increases in the production of adrenaline-related hormones with ageing have been thought to explain the apparent ability of older men to perform freak feats of strength.

"However, there is no experimental data demonstrating that increased production of these hormones actually enhances strength in older adults.”

They point out that we also start losing muscle mass from the age of 40, in a process called sarcopenia, so that “the size of our muscles at the age of 80 can be about half of what they were at 40”.

Wilkinson and Atherton think many of the older men who hit headlines for their strength, have actually been training consistently for decades, allowing them to hold onto their muscle mass for longer.

“Performing regular weight training into older age also increases strength and muscle bulk. In fact, weight training in older adults has been shown to increase hormone levels to an equivalent level to that of untrained younger adults.”

So should we all hit the gym then?

Dr Eugster certainly thinks we should start doing more exercise now.

“You don’t have to wait until you are 97,” he told the Daily Mail. “If anything, I’d suggest starting decades earlier. But my point is that you can still do it, whatever your age. This idea that you have to wither as soon as you turn 60 — nonsense!”

Wilkinson and Atherton believe gym membership isn’t necessary, it’s about just getting more active in older age: “Performing low-level exercise programmes or even everyday manual tasks can increase strength and mobility in the ageing population providing a healthy and independent older age.”