Proximal stability and distal mobility is a principle that’s often used in corrective exercise. It means that training your core to be more stable can affect your distal joints providing more mobility.
What is proximal stability? I believe it’s the connection between the lumbar, pelvis and hips. With this belief if you have a solid core, you should feel stable down in your feet and out through your hands and head the distal joints.
Think about a baby. Babies have a ton of mobility but not a lot of stability or muscle control.
They develop stability first in their heads and trunk. Once they have a stable base, they can start to roll over, sit up, reach for things , pull themselves up, stand and walk. This can only happen once they have proximal stability.
Without strength, stability and mobility at the core, many extremities will work over time. The fatigue of a weak core creates a lot of tension in joints and tissues in our bodies and possible pain.