Estonian triplets take on 26.2 miles

The women’s marathon on Aug. 14 will be a special moment for Estonians Leila, Liina, and Lily Luik. When they line up at the start, it’s believed the blond-haired, blue-eyed sisters will be the first identical triplets to compete against each other at an Olympics. Equally impressive, the 30-year-olds only started distance running seriously about six years ago. Leading up to qualification for the Games, their training motto was “Trio to Rio.’’ Double takes to come.

Perfect Olympic prep: pro football

From rugby to track, NFL experience serves some athletes well. Patriots safety Nate Ebner will play for the US rugby team in Rio. And he will share a special distinction with former NFLer and bobsledder Herschel Walker. They are the only men to compete on the US Olympic team while active NFL players. Former Detroit Lions running back Jahvid Best will run the 100 meters for Saint Lucia.

Ten athletes form first refugee team

The first-ever refugee Olympic team will compete. A yearlong search led to a group of 10 athletes — five track runners from South Sudan, two swimmers from Syria, two judokas from the Democratic Republic of Congo, and a marathoner from Ethiopia — and a collection of personal stories that astound. The Refugee Team will march in the Opening Ceremony under the Olympic flag right before Brazil enters.

US surpasses China for female athletes

Of the 555 athletes representing the US in Rio, 292 are women. In the history of the Olympics, that is the largest number of women to compete for a single country. The 292 women break the record set when 289 Chinese women went to the 2008 Beijing Olympics. And the 292 are 23 more than the US sent to the 2012 London Olympics.

Youth served on US track squad

The US track and field team is considered the toughest squad to make. But try telling that to a couple of teenagers headed to Rio. There is 16-year-old Sydney McLaughlin, who made the team in the 400-meter hurdles and became the youngest US track and field Olympian in 44 years. McLaughlin will be joined by fellow teenager Vashti Cunningham. The 18-year-old is the reigning indoor world champion in the high jump and daughter of former NFL quarterback Randall Cunningham. The youngest member of the US Olympic team is table tennis player Kanak Jha, who turned 16 on June 19.

Good aim,

and good genes

For the eighth time, Georgian shooter Nino Salukvadze will compete in the Summer Games. But the 47-year-old’s longevity isn’t what generates attention these days. Instead, it’s her Olympic teammate and 18-year-old son Tsotne Machavariani. For the first time in Olympic history, a mother and son will compete together at the same Games. Machavariani can only hope to follow the success of his mother, who won gold and silver in 1988 at Seoul and bronze in 2008 at Beijing.

Gymnastic barrier-breaking

Before Jamaica’s sprinters take the track, its gymnast will make history. Yes, gymnast. Toni-Ann Williams will be the first gymnast to compete for the Caribbean nation at the Olympics. The Maryland-born athlete with Jamaican parents usually competes for the University of California. India also has its first Olympic qualifier in gymnastics, daring vaulter Dipa Karmakar. Both will compete against 41-year-old Oksana Chusovitina of Uzbekistan, the oldest female gymnast in Olympic history.

No headgear, and hardly any pros

Men’s boxing will look a little different in Rio. For the first time since 1980, the fighters won’t be wearing protective headgear. And 112 years of amateur Olympic boxing competition will come to an end, though ­only three pros are signed up to compete.

SHIRA SPRINGER

Shira Springer can be reached at springer@globe.com. Follow her on Twitter @ShiraSpringer