Kate Plays Volleyball in Sky-High Wedges

Update Friday October 18, 2013 11:00 AM EDT Originally posted Friday October 18, 2013 09:05 AM EDT

Kate was back in the swing of things Friday – when she played volleyball in sky-high wedges.

The Duchess of Cambridge, 31, left Prince George at home in Kensington Palace with Prince William for her first solo royal outing since giving birth in July. And she showed she's back in shape as she leaped into action at the net.

The sports-loving princess was in her element among the athletes as she joined her charity, SportsAid, in the familiar surroundings of London's Olympic Park.

Looking casual in navy jeggings by J Brand, a Breton-style top by Ralph Lauren and a one-button blazer by Smythe (she wore a similar outfit during a visit to the Olympic village in August 2012), she first chatted with young badminton players before moving on to speak to some wheelchair basketball players.

And then, it was on to volleyball and some surprise gameplay in her 4-inch Russell & Bromley wedges.

"She was really good," Jordan Dalrymple, a volleyball player who's benefitted from SportsAid, told PEOPLE of Kate's effort at the net. "She told me she has played beach volleyball before. We were quite impressed. She had the basic skills down – and in heels."

Kate became patron of SportsAid earlier this year after being inspired by the success of Team G.B. and ParalympicsGB at the 2012 London Games, where she and husband William regularly cheered on the British athletes.

Royal sources say that the care of Prince George, who will be christened at the Chapel Royal at St. James's Palace on Oct. 23, will take priority but Kate will appear in a few more royal engagements before Christmas.