As the Flatiron District gets more residential development and young technology, advertising, media and information (TAMI) firms, it is getting, well, fitter.

The Shadowbox boxing studio signed a lease for its first location at 28 W. 20th St., where it will open for business this spring.

Ross Berkowitz and Ernie Getz of RKF represented the gym, which will offer classes in its 6,500 square feet.

Winick Realty Group’s Ross Burack and Kelly Gedinsky represented the building owner, Pan Asia Estate, in the lease that had an asking rent of $160 per square foot.

Soul Cycle, Equinox and Barry’s Bootcamp all have space nearby, while The Fhitting Room was brought to the adjoining building at 31 W. 19th St. by Gedinsky and Burack.