According to Official Guinness Records,
The record for the fastest wheelbarrow race over 100m is 14 seconds by Otis Gowa and was filmed on location for Guinness World Records at Davies Park, Mareeba, Queensland, Australia on 15 May 2005.The person pushed in the wheelbarrow was Stacey Maisel, she is 41 years old and weights 50kg.
For a complete list of 2005 records, please visit 2005 Guinness Records in Australia.