No. 5 in our series of core activation exercises – the side plank. Posted on August 21, 2019September 3, 2019 by Legras Family No. 5 in our series of core activation exercises – the side plank. This is often an under developed area and helps to strengthen your shoulder girdle and obliques. 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)