In this short video you will not only see but feel that when you lean forward it begins increases compressive type forces going into the wrist. This is a cue typically given when going from a Hi-lo chaturanga. This is an advanced option and is not ideal to be used in class as the only option. There are too many strength abilities in class for this to be the only option.
Why is this cue given? The idea of stacking your joints is the safest place to start. While this is safe way to start a movement for the knee in Warrior (lunge) type poses and some squat oriented poses; it is not for the elbow for hi-lo chaturanga.
Stacking the elbow on top of the wrist joint during the hi-lo chaturanga can be stressful and traumatic on the wrist, the shoulder and the neck if you do not have a strong foundation of strength at the peripheral core (upper back). The elbow is a far sturdier joint than the knee. Implementing the idea of stacking the elbow over the wrist is a lack of understanding of how the body works and has different implications.
As we hinge forward in the joint to take the stress off the elbow we are adding stress somewhere else. That stress simply doesn’t disappear. The lever at the shoulder is increasing (this means you are increasing the weight) and the stress at the wrist is also increasing. If you do not have the peripheral core strength to account for this you are going to kill your wrist, shoulders, and neck because the stress must be taken up somewhere.
The joints that need to be stacked here is the shoulder over the wrist, which means the elbow is behind the wrist joint as you lower yourself to low chaturanga or low plank. This is a far more pleasant position to be in, especially when learning or having pre-existing issues in the wrists or the shoulders. The stress that is going behind the wrist and makes the movement more accessible to the beginner as well. As you develop more and more strength hinging forward is a nice challenge. It is also helpful to develop strength in the hinge forward position when you are wanting to take on more challenging arm balances or inversions. Development not just central core but the peripheral core strength is crucial for the hinge forward.
Remember this is simply a snapshot of something that's a little bit more complex than a one-minute video.