Planking is hands down one of the best exercises you can do for your core, but it also strengthens and tones your back, glutes and shoulders.  No matter what type of workout you're into, there's always room for a plank.  During class at The Bar Method Hoboken, we do two planks and sometimes our teachers even sneak in a (much welcomed) third.  Here, owners Melissa and Lucy share everything you need to know to make sure you're getting the most out of the exercise.  From form to timing, we got you covered.