Kate Middleton stunned in a slim body at an athlete workshop held at the Copper Box in the Olympic Park in London on 18 October. (Photo: REUTERS)

Kate Middleton showed off an impressively flat midriff as she reignited her love for physical activity at a sports workshop at the Copper Box Arena in Queen Elizabeth Olympic Park, London.

The Duchess of Cambridge was at the SportsAid Athlete Workshop, her first sporting engagement since giving birth to Prince George, the third in line to the British throne, in July.

SportsAid, of which the Catherine is a royal patron, is a charity organisation that recognises the achievements of the next generation of British athletes and helps them compete at international sporting events. The workshop was Kate's first visit to the organisation as its patron.

During the workshop, the duchess joined more than 70 athletes, including several Olympians and Paralympians such as Katherine Grainger, Ade Adepitan and Karen Pickering. Kate watched them taking part in a number of sports activities, including wheelchair basketball, CP football, volleyball, fencing and badminton.

Heads turned when Middleton gave volleyball a go.

Wearing a striped T-shirt, navy blazer and blue jeans, a toned-looking Kate took to the court without changing out of her suede navy wedges.

According to the organisers, the duchess played several rallies with a group of the organisation's athletes that included England men's volleyball squad member, Jordan Dalrymple.

Middleton has played such games at her official engagements in the past. During a visit to her old school in Pangbourne, Berkshire, in 2012, the duchess famously joined children for a game of hockey, probably her favourite sport, while wearing high heels.

See photos of Kate playing volleyball here.

The midriff says it all! Kate Middleton has surely lost all pregnancy weight. (Photo: REUTERS)
The midriff says it all! Kate Middleton has surely lost all pregnancy weight. (Photo: REUTERS)
Kate Middleton reunites with her passion for sports as she plays volleyball at the workshop. (Photo: REUTERS)
Kate Middleton reunites with her passion for sports as she plays volleyball at the workshop. (Photo: REUTERS)
Kate Middleton poses for a group photograph with young athletes. (Photo: REUTERS)
Kate Middleton poses for a group photograph with young athletes. (Photo: REUTERS)
The Duchess of Cambridge is helping to shine a light on the achievements and potential of young athletes throughout the UK. (Photo:REUTERS)
The Duchess of Cambridge is helping to shine a light on the achievements and potential of young athletes throughout the UK. (Photo:REUTERS)
Kate has been a sport enthusiast since her school days. (Photo:REUTERS)
Kate has been a sport enthusiast since her school days. (Photo:REUTERS)
Kate opted for a sporty style statement for the event. (Photo:REUTERS)
Kate opted for a sporty style statement for the event. (Photo:REUTERS)