Britain's Pippa Middleton will begin a cycle ride across the US tomorrow (14.06.14).
The 30-year-old party planner - who is the younger sister of Duchess Catherine - and her brother James are part of an eight-person team who are undertaking Race for America, a gruelling 3,000 mile journey from Oceanside, California to Annapolis, Maryland.
The siblings are in a team with their friend James Matthews and are taking part in the event on behalf of a charity named after their friend's brother, who died in 1999 during a descent from Everest.
The sporty socialite has previously taken part in a number of tough physical challenges, including an endurance ski race, the Highland Cross run in Scotland and Switzerland's Engadin Marathon.
The brunette beauty recently confessed she was concerned
cycling would leave her with "massive" thighs.
She wrote in her now-defunct column for the Daily Telegraph newspaper: "The physical benefits are obvious: regular cycling strengthens the heart and lungs, meaning oxygen is transported more efficiently around the body. This contributes to a decrease in blood pressure and boosts fat burning, while improving muscle tone in the legs, thighs and buttocks. Which is well and good, but how do you avoid developing massive thighs like many of the Tour de France chaps?"
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