BEFORE he reached his teens, Douglas Edmunds was lugging milk crates up Castlemilk closes.

Top-floor deliveries helped build muscles. Drinking the stuff did no harm either, and the milkman's laddie grew into a brawny specimen for whom combative trials of strength became an obsession.

This was something of a family totem. His father, nicknamed "Big Tony" after two-ton Tony Galento, had fought in boxing booths. His grandfather was reputed to have been among a group of nationalists (including poet Hugh MacDiarmid) who plotted to steal the Stone of Destiny. He was to be the muscle helping remove it from Westminster Abbey, and trained by lifting ingots at Glasgow's Beardmore forge.

Whether by accident or design, Dougie remained true to his forebears, continuing family affinity with pugilism and iron. He was Scottish Universities' boxing and national weightlifting champion while gaining a doctorate in metallurgy; then multiple Scottish shot and discus champion and an international highland games heavy, winning the world caber title.

An innovative sport entrepreneur, he helped build the global appeal of televised strength events, and many of the world's strongest men beat a path to his Carmunock home, on Glasgow's outskirts.

The garage there was a gym, and repository for hammers, weights, stones, and cabers. An adjacent field saw service as a throwing arena where visiting celebrities learned the techniques of highland games. And where his son, Gregor, was brought up in the faith, introduced to cut-down impliments. In a moment of weakness, having sought a skateboard for his 10th birthday, Gregor accepted a shot putt.

The lore surrounding these big men, often with appetites and egos to match, spawned a self-deprecatory autobiography, The World's Greatest Tosser. That was several years ago, but now comes the sequel, a tribute to the enduring mystique of strong men, and a search for the greatest of them.

Giants and Legends, published privately, is sometimes whimsical, usually humourous and irreverant, and invariably close-to-the bone. It celebrates epic achievement, pleasure in the company of outrageous kindred spirits, but also their human frailties. Edmunds had to obtain assurances from larger-than-life figures that they would not sue.Samson and Hercules, the 7ft 9in Hebridean giant Angus MacAskill, Donald Dinnie, and Louis Cyr, were the stuff of Edmunds' boyhood dreams. MacAskill was asked by Queen Victoria to impress her with his strength. He ground a dent into the floor with his heel.

Edmunds became a formidable highland games contestant and, with David Webster, helped establish the genre internationally. Yet in doing so, Edmunds found others were more than a match for him. This discovery and his journey through strength sport makes his book fascinating, even for those not steeped in its culture.

Hamish Davidson was a creature of prodigious strength and Gargantuan appetites. When European shot champion Geoff Capes crossed the professional divide, he expected to take highland games by storm. Fortified by a bottle of gin, Davidson toppled Capes at his debut games in Edinburgh's Princess Street Gardens. This happened to be Davidson's birthday. He celebrated with 20 pints of lager and by chain-smoking cigars, then competed next day in London, in Britain's Strongest Man. He won the battery hold with a world record, and only in the final event – a man-to-man tug of war, in which Capes had bodyweight advantage – did Capes edge ahead.

A damaged Ferrari and E-type at his mink farm bore testimony to Davidson's driving and drinking. Police constantly tried to catch him. Once he was spotted swigging a can of lager. When police opened the door he was "knee-deep in empty cans," as Edmunds recounts. "They were aghast to find the steering wheel on the other side." Holland's strongest man, Wout Zijlstra, was driving the left-hand drive car.

Davidson may be worthy of a book on his own. He once had to borrow money because a prostitute was spraying his room with dye, as he declined to pay. Yet this roughest hewn of diamonds with the soft highland accent had an ability to charm sophisticated, aristrocratic women with a regularity which beggared the belief of contemporaries. However, one wife was dispatched home with her mother inside a month. The mother-in-law had appeared a match for Hamish until he deposited a pile of excrement at the head of the stairs.

The Icelandic giant, Jon Pall Sigmarsson, possessed biceps so large that he had to hold a mobile phone to the ear opposite the supporting arm. It was he who deposed Capes as World Strongest Man. Sigmarsson fell in love with Scotland and highland games, and when he appeared on STV, the switchboard was jammed by callers.

His charismatic personality was as legendary as his strength, and when he died aged 32, Edmunds recalls the strongest of men weeping during the funeral at Hallsgrim's Kirk, above Reykjavik.

Edmunds was so upset he announced retirement from strength promotion, but was coaxed back by participants who felt the sport would be more dangerous without him. It was demonstrated, contrary to rumour which seemed to assume the status of fact, that steroids were not to blame. Edmunds reveals there was a prolonged familial history of heart problems.

He also reveals that Davidson has found religious redemption. Edmunds concludes that the title of greatest athlete may have to be resolved by a celestial contest, with the Almighty as referee. Davidson suggests that some contestants may be unavailable in heaven, but that he has no intention of missing it.

The catalogue of escapades, brutal conflicts, heroic endeavour, political skulduggery, marriages wrecked, brushes with the law, and sometimes frankly nauseating laddish behaviour, does fill a book. But there is also remarkable humanity and humility. There has never been a more insightful picture of strength sport.

n Giants and Legends, £19.99, from Waterstones.

THE FAMILY WAY The Edmunds have been at the heart of strength sport for generations. Now, a new book paints a candid picture of the activity's exponents, writes Doug Gillon