No. 3 of our Core Activation series, assisted roll up / roll down focussing on the rectus abdominis muscles. Posted on August 7, 2019September 3, 2019 by Legras Family No. 3 of our Core Activation series, assisted roll up / roll down. Rather than doing a sit up, this assisted exercise allows you to really focus on the rectus abdominis muscles. Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to email a link to a friend (Opens in new window)