HIIT IT! has been selected to be a part of Union Square Sweat Fest this year! 😅👏💪💦Free HIIT IT! at JackRabbit Union Square Sunday 2/21 9AM. First come, first serve. Union Square Sweat Fest is an annual week long showcase of Union Square’s vibrant health and wellness scene featuring NYC's most sought after classes and instructors presented by the Union Square Partnership/FitPlusLove and sponsored by Adidas.