Popsugar Fitness Celebrity Instagrams Best Celebrity Ab Workouts on Instagram 10 Celebs Share Their Awe-Inspiring Abs — and the Exact Moves That Helped Them Get There November 20, 2019 by Maggie Ryan View On One Page Photo 12 of 14 ADVERTISEMENT () Start Slideshow View this post on Instagram A post shared by Britney Spears (@britneyspears) on Mar 6, 2017 at 3:19pm PST Share This Link Copy ← Use Arrow Keys → 12 Britney Spears Does Seated Knee Tucks For Max Core Strength Seated knee tucks are hard enough as it is, so of course Britney Spears went and did them on a bench to add an extra element of balance and stability. Previous Next Start Slideshow Celebrity InstagramsWorkoutsCelebrity FitnessAb WorkoutsAb Exercises