Life The workout that ClassPass deems 2019’s trendiest? It’s a doozy December 4, 2019December 4, 2019Carly Mallenbaum, USA TODAYComments Off on The workout that ClassPass deems 2019’s trendiest? It’s a doozy Fitness app ClassPass analyzed more than 100 million workouts to determine 2019's fastest-growing fitness class.