One of the first positions of Yoga is the "Yoga plank position". It is the position used to strengthen the lumbar muscles, creating structure for the next steps.
In practice, in this traditional position, you should hold your breath for a moment before moving on to other positions. It can also practiced on its own to build the strength and endurance of your body.
In a fuller description, the "Yoga plank position" is a position of equilibrium in the arms toning the adbominal muscles while strengthening arms and spine. It's name comes from the word "kumbahk", which means "breath holding" and "asana", which means "pose".
Strengthening your muscles is the main benefits of this exercise.
You can see in the video below how you can easily start this execise.