It began as a 10-week competition, presented as part of the CBS Sports Spectacular. However, the World's Strongest Man tournament has spun off into an international, annual event, no longer confined to the US.
Originally, the field was a mix of weightlifters, football players, and pro wrestlers, such as Superstar Billy Graham, Ivan Putski, Ken Patera, Tom Magee, and, in the 1979 event shown below, Jerry "Crusher" Blackwell. While Patera was billed as a wrestler competing in the 1977 inaugural event, I cannot be certain if host Brent Musburger brought up Patera's accomplishments as a weightlifter, earning a gold medal in the 1971 Pan American Games, and being on the 1972 US Olympic Team. I didn't watch every week. Anyway, Patera placed 3rd, the best showing among the wrestlers. Magee, better known as a bodybuilder than a wrestler coming from Canada, matched Patera's finish a few years later.
The 1977 field also included actor-bodybuilder Lou Ferrigno (The Incredible Hulk), but if memory serves me correctly, the competition took place prior to the launch of Hulk as part of CBS' primetime lineup (it was a mid-season replacement).
Franco Columbu, prominently featured, along with Arnold Schwarzenegger, in the movie, "Stay Hungry", was injured early in the 1977 tournament, and was forced out. A similar fate befell Blackwell, as you may see in this video compilation. The graphics are from a rebroadcast on ESPN2. Either Musburger's original commentary was edited off, or he didn't return for the 1979 tournament.
While Bill Kazmaier finished 3rd, he'd go on to win the next three in a row. He'd also give wrestling a try, an ill-advised career decision that saw him land in WCW in the 90's.
Today, the tournaments still take place, and, after airing on ESPN2 for a few years, the American TV rights now are back with CBS, which runs the tournament on CBS Sports Network. To think the event reached its 40th anniversary last year.