Issue
Why can't I bend my knee / raise my back foot?
Lowering Your Chest
Mechanism / Why It Happens
When you try to lift your legs, your chest naturally tends to lower. Your legs won't lift properly if you move against this mechanism.
For any object in the air, moving one part requires another part to move in the opposite direction. This is due to the principle of conservation of momentum, which means that an object in the air must maintain its total momentum. The same principle applies to an ollie. Once you're airborne, tucking your knees toward your chest naturally creates a tendency for your chest to lower. Therefore, if you perform a movement that causes your chest to rise while your knees are trying to lift, it becomes harder to tuck your knees and bring up your back foot. For more details, see this Tip (Link).
