David Keohan surveyed the County Waterford beach and spotted a familiar mound half-buried in sand: an oval-shaped limestone boulder. It weighed about 115kg.

He wedged it loose with a crowbar, wiped it dry with a cloth, dusted his hands with chalk and paused to gaze at the Irish Sea, as if summoning strength from the waves pounding ashore.

He hunkered down, gripped the boulder and hoisted it to his lap. Legs trembling, Keohan straightened his knees and hoisted the weight up to his chest, close enough to kiss it. Two seconds later he lowered and dropped the boulder, which thudded back on to the sand.

It was a demonstration of the ancient sport of stone lifting. Keohan has almost single-handedly revived the practice in Ireland and helped stir global interest.

“It’s not just about strength. Every single lifting stone has an amazing story attached to it,” said Keohan, 47. “It’s opened up a whole culture that was lost.”

To his fanbase Keohan is better known by his Instagram handle Indiana Stones. On there, he is a scholarly Hercules who parses myth, folklore and literature to locate boulders around Ireland that for centuries were used to test strength and bond communities.

Some were lifted at funeral games to honour the dead, some to celebrate harvest festivals and some to mark a chieftain’s ascension, said Keohan. “One stone was almost like a job interview to become a stonemason – you had to be strong enough to lift it.”

To lift a designated stone – some weighed up to 170kg – a few inches above the ground was known as “getting the wind under it”, said Keohan. “That was a great day in a young man’s life. If you lift it to your knees, you’re a champion. Lift it up to your chest, you are a phenomenon of strength and spoken about for generations to come.”

He has identified 53 lifting stones, spanning beaches, fields and graveyards, and hopes to locate dozens more. To lift such a stone today is to connect with all those who previously managed the feat, a continuum that in some cases stretches back millennia, said Keohan. “Isn’t that amazing?”

Few in Ireland had heard of the sport until Keohan stumbled into it.

When Covid restrictions shut gyms in 2020, the former kettlebell lifting champion started using stones in his garden as weights. Galvanised by documentaries about stone lifting in Scotland, Iceland and the Basque region, he made a post-Covid “pilgrimage” to the 127kg Fianna stone in Scotland. “It was strength, mythology, history. I fell in love with it.”

After reading Liam O’Flaherty’s 1937 short story The Stone, about an elderly man who tries to lift the “manhood stone” of his youth, Keohan tracked down a pink-tinged granite lump that matched the story’s description on the Atlantic island of Inishmore, where O’Flaherty grew up.

Now, a sport that was all but forgotten boasts a devoted following on Instagram and TikTok, and a competition organised by a group called Irish Stone Monsters. The ride-sharing company Lyft has sponsored a stone lifting studio at a Dublin gym.

Enthusiasts trek to remote rural areas to try to lift designated stones. A stone in County Clare named after Mrs Kildea, a possibly apocryphal figure who reputedly lifted an enormous boulder, has inspired women to take part. Last year a boulder known as Cloch Bán, or White Stone, was shipped to enthusiasts in Boston.

Stone lifting practices existed across Europe, Asia and Africa, said Conor Heffernan, a cultural historian at Ulster University. The legend of the warrior Finn McCool creating a path to Scotland by laying basalt columns in the sea – the Giant’s Causeway – illustrates Ireland’s connection to its rocky landscape, said Heffernan. “Most of our surviving memory is either oral histories or texts that were collected from the 1800s onwards.”

Stone lifting in Ireland was on occasion a proxy for colonial rebellion, said Heffernan. “There’s a famous story where the Catholics in a community find the strongest Catholic man to lift a stone that no Protestant can.”

Keohan and Heffernan are seeking to get stone lifting included in Ireland’s inventory of intangible cultural heritage – a first step to Unesco recognition.

Guided by local lore, the National Folklore Collection, and tips from Instagram followers, Keohan has found dozens more stones around Ireland. “This dam burst of information came out,” he said. “It has given me purpose and a reattachment to what it means to be Irish. I’m just showing people the story and to me that has become more important than the actual lifting.”

The father of three, who works at a construction depot in Waterford, has tapped into a passion for Irish culture that has also boosted the Irish language, road bowling and TikTok’s #GaelTok content.

Keohan has written a forthcoming book, The Wind Beneath the Stone. “I have this mad double life where I’m still working the same job during the week but at weekends I could be anywhere.”

When he was nicknamed Indiana Stones, Keohan embraced the moniker. His application to do a PhD could burnish it. “Yeah,” he grinned, “Dr Indiana Stones.”