The first race happened on May 31, 2011 and the clothes were donated to charity.

On Tuesday at 20:30 the students started outside Aulario II with clothes they wished to donate and removed them before racing to the finish line for a fnac gift voucher worth €30.

Source:

https://vanessacastillo.wordpress.com/2011/06/01/primer-carrera-nudista-1st-nude-race/

https://uniprogres.blogspot.com/2011/05/carrera-nudista-en-la-ua.html