One of Kayla Itsines' latest Instagram challenges is an at-home ab challenge, which includes a series of exercises which she says need 'minimal equipment but maximum effort.' — Picture via Instagram/Kayla Itsines

NEW YORK, May 4 ­— If you’re looking for a new workout challenge this weekend, then head to Instagram to see some of the recent ab workouts from celebrity trainers and fitness influencers David Kirsch, Kayla Itsines and Jen Widerstrom, which are easy to do at home but will still effectively work your core.