Duchess Kate, who once played field hockey in high-heeled boots, today took to a volleyball court in platform wedges in the cause of charity.

The Duchess of Cambridge is back on form, turning up for a sports charity event in her first solo engagement since the birth of Prince George in July.

As a patron of sports as one of her charity areas, she attended a SportsAid Athlete Workshop at Queen Elizabeth Olympic Park in London. It's her first visit to a SportsAid event as its royal patron.

Pregnant only three months ago, her figure has returned to its former slender silhouette. She was dressed casually in a navy-blue Smythe jacket over a Ralph Lauren sailor-style top with navy stripes, skinny blue jeans and her familiar Stuart Weitzman navy wedges with the cork platforms.

According to HRHDuchessKate blog, which tracks her fashion, she's worn all of the components of her outfit before, so she has returned to her frugal habit of recycling her clothes that her fans so admire.

Soon after she arrived at the event, British reporters began tweeting out pictures of her on the volleyball court jumping to punch the ball, her top lifting up to expose her flat stomach and waist.

"#royal #kate's played hockey in high heels, now it's volleyball in wedges," tweeted Paul Harrison, royal reporter for SkyNews.

A former field hockey player in high school, Kate took a turn playing with a team on a visit to her old grammar school while she was in early stages of pregnancy, wearing high-heeled boots and a plaid coat.

Today she watched young athletes taking part in various sports, including wheelchair basketball, football, volleyball, fencing and badminton, and then joined them and their parents for workshops about media and social media training, nutrition in sport and general guidance from Olympic and Paralympic athletes.

SportsAid, founded in 1976, helps train future generations of British athletes by recognizing young athletes with potential and supporting them early. It's been the secret behind some of Britain's most successful athletes, including two-thirds of the British team at the London 2012 Olympic and Paralympic Games, some of whom were at the workshop.

The big event on her calendar next week is the christening of Prince George on Oct. 23 in a private family ceremony in the Chapel Royal at St James Palace, where the body of his late grandmother, Princess Diana, lay in state before her funeral in 1997.

The duchess also will make a public appearance next week when, as patron of 100 Women in Hedge Funds Philanthropic Initiatives, she will attend a gala for Action on Addiction (another of her charities) in the Kensington Palace State Apartments.

These are the formal Georgian-era state rooms in the palace, where she and husband Prince William have recently moved into their newly renovated residence, the 21-room Apartment 1A.

The state rooms, including the Presence Chamber, the King's Drawing Room and the Cupola Room, are run by the charity Historic Royal Palaces and will be used for other charity receptions hosted by the royal couple.

Next month, they are expected to host a winter wonderland-themed party inspired by the ice palace in the film Dr Zhivago, to raise money for Centrepoint, the homeless charity William has taken on since the death of his mother, Princess Diana, who was its patron. Bon Jovi is set to perform in the garden at the party.

Kate has been seen in public only a handful of times since Prince George was born July 22, and only with William. Most recently, they dressed up for an awards dinner hosted by William's wildlife conservation charity, Tusk Trust.

William has carried out a number of solo engagements, however, including on Thursday when he stepped in for his grandmother, Queen Elizabeth II, to host his first investiture, or honors, ceremony at Buckingham Palace, which included dubbing his first knights with a ceremonial sword.

As president of the Football Association, he also hosted a soccer game in the back garden of the palace, and is scheduled to attend a dinner marking the association's 150th anniversary next week.