Crown Princess Mary and her family get physical for Denmark's annual Royal Run event

Crown Princess Mary and her family have put on their running shoes to take part in several big races across Denmark for the Royal Run.

The annual event has become a favourite among the royal family and the Danes since it was created to celebrate Crown Prince Frederik's 50th birthday in 2018.

Just days after Denmark's future King turned 55 on May 26, he and his family have once again pounded the pavement for the popular event.

Watch the video above.

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More than 93,000 Danes took part in the Royal Run, which was held at five locations across Denmark this year.

Participants can choose to run or walk three distances: the one mile (1,609 km), five kilometres or 10 kilometres.

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Crown Princess Mary did something a little different this year by running in the shortest race in Nyborg, west of Copenhagen, before being flown by helicopter to complete the five kilometre walk in Nykøbing Falster, south of the capital.

"It was actually a wonderful experience," Crown Princess Mary told Danish television network TV 2 after crossing the finish line in Nykøbing Falster.

"I've run it many times now so it's great to try [something new] and see how it goes. It was a pleasure, you experience it in a completely different way."

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She then returned to Copenhagen to cheer on her husband and youngest son Prince Vincent who were competing in the 10 kilometre race through the city, which ended at the royal family's home Amalienborg.

Crown Princess Mary was at the finish line where she hugged Prince Vincent, 12, who beat his father in the race.

Earlier in the day Prince Vincent had joined his three siblings for another run through Copenhagen.

It was the first time Prince Christian, 17, Princess Isabella, 15, Princess Josephine, 12 and Prince Vincent took part without their parents.

But Crown Prince Frederik was keeping busy elsewhere.

He competed in not one but three races throughout the day, running in Aabenraa and Herning before ending with the 10-kilometre route in Copenhagen.

No doubt the royal family would have been exhausted by the end of it.

They were cheered on by Queen Margrethe II from afar, who watched the day's events from the comfort of Fredensborg Palace, north of Copenhagen, where the royal family typically stay during spring.

A photo shared by the palace showed the Queen watching on television.

The monarch, 83, is still recovering from major back surgery that she had in February.

Since the operation Queen Margrethe has returned to royal duties but has a much quieter calendar than usual.