If you think planks are easy, you’ve probably never done them before.  Have fun with this one! This workout will have a 1:1 work/rest ratio. PERFORM PER ROUND: 20 sec – Plank 20 sec – Elbow Plank 10 sec – Plank 10 sec – Elbow Plank Rest 1 minute between rounds. NUMBER OF ROUNDS: Beginner…