It doesn't seem like a big difference… One of the hardest truths to convince a beginner in Jiu jitsu of is that there is a world of difference between being FLAT ON YOUR BACK underneath an opponent, as opposed to BEING ON YOUR SIDE. To the untrained eye they look pretty much the same. You are lying down underneath an opponent in cases after all. In fact the difference will determine how effective you will be from bottom . When you're on your side you can bear an opponents weight much more easily. You can move side to side far more readily. You can prop yourself to an elbow or turn easily up to your knees, or out with your legs and catch an opponents leg. You can create an action/reaction sequence by turning from one side to another. In short – you don't bear weight directly and you can move much more readily. Understanding the of this fundamental insight and making it part of your daily training is absolutely critical to your in most Bottom positions, particularly those your opponent is threatening to pass your legs. Next you're suffering under an opponents weight – turn to your side (almost always towards your opponent) and you'll feel an immediate easing of pressure and a newfound to move with effect