No. 5 in our series of core activation exercises – the side plank. Posted on August 21, 2019September 3, 2019 by adventurousangel96822ae11c 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: Share on X (Opens in new window) X Share on Facebook (Opens in new window) Facebook Email a link to a friend (Opens in new window) Email