Kate revealed that she and Princess Charlotte are both capable of doing the splits.
The revelation came during a visit to a Port Talbot leisure and fitness centre.
Kate revealed her hidden talent to students at Tywyn Primary School.
According to Tim Lawler, Princess Charlotte is interested in gymnastics.
At the leisure center, William and Kate took part in a spin class challenge.
Kate took first place in the 45-second race and was awarded a gold cup.
The royal couple paid a visit to South Wales to promote mental health initiatives.
William has been named the new patron of Wales Air Ambulance.
This is William's first Welsh patronage since he was appointed Prince of Wales.