How does rugby 7s compare to its distant cousin American football?
Rugby union and American football share many common traits.
Both are tough, uncompromising sports that produce breathtaking displays of physicality and athleticism.
A number of players have switched between the two in recent years.
But the link runs deeper. Did you know that American football can trace its origins, in part, to rugby?
Nate Ebner's cross-over
More on that historical link in a moment, but first it's worth highlighting that Nate Ebner is currently the only active NFL player to have competed at the Olympics, and he did it in rugby.
The New England Patriot took a leave of absence from his normal job to play for the USA rugby sevens team at Rio 2016.
The former USA rugby schools representative scored a try in the group stages against eventual men's winners Fiji.
Rugby sevens @ Rio 2016 - Pool Stage (Men) - FIJ vs USA
Rugby sevens @ Rio 2016 - Pool Stage (Men) - FIJ vs USAFiji (FIJ) - 24United States (USA) - 19
The original bond
During the 1860s, American colleges were playing an early code of American football that was similar to football (or ‘soccer’ in America).
By the 1870s, colleges decided to start incorporating rugby-style rules of carrying the ball.
The rule changes were written up in 1880 by Walter Camp and the modern version of American football was officially born.
The basics of both rugby union and American football remain the same.
Both sports use an oval-shaped ball, which can often be difficult to catch and kick.
Defensively both sports feature physical collisions, where players stop opposition ball-carriers with a tackle.
Offensively, teams aim to get the ball into the opposition’s end of the field and over a line. This is known as a touchdown in American football, and a try in rugby.
A designated player then gets the opportunity to score further points for their team by kicking the ball through posts in both sports.
In American football passing the ball forward is legal, whereas rugby players may only pass backwards to one another.
One of the biggest differences between rugby and football that successful tackles end a play in American football, but not in rugby.
In terms of equipment, rugby favours a more minimal approach than its American cousin.
American football players are required to wear helmets and large shoulder, body and leg padding.
In rugby there is no mandatory protection, although many players favour to wear a gum shield.
America's golden tradition in Olympic rugby
Traditional 15-a-side rugby made several brief appearances at the Olympics in the early twentieth century.
The USA won two gold medals at the Antwerp 1920 and Paris 1924 Olympics.
With rugby's next Olympic appearance (in the shorter 'sevens' form of the game) coming in 2016, that made America rugby Olympic champions for 90 years!