Zach Wilson is gonna love this.
65-year-old fitness legend Denise Austin showed off her incredible physique while strutting the runway alongside her daughter at Miami Swim Week ... throwing on a bikini and absolutely crushing it!!
The workout video icon walked alongside 29-year-old Katie -- a Sports Illustrated Swimsuit rookie -- over the weekend ... making them the first mother and daughter to rock the runway together at the event.
Of course, Austin became a household name after making more than 50 fitness tapes over several decades .