Coach Note: When to allow the low back to round? If you choose to round the lower back you MUST still feel the stretch in the hamstrings and/or adductors. I do not recommend rounding the lower back, BUT it does allow for more individuals to get into this position initially.
Simply getting into the pancake position is the first step toward progressing to a flat back position in the pancake stretch. So the low back being SLIGHTLY rounded allows for more individuals to start to stretch the hamstrings and adductors in the pancake position and it allows more individuals to stay in this stretch position for the required amount of time to make change to the central nervous system and muscle tissue.