Back Pain
     

What did he say?

Some of the terms used might not be familiar to you. I'll explain them to you.
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What?   Explanation in English
     
Pronation   Flat Foot caused by ankle bending inwards
     

Sagittal Plane

Pelvic Tilt

Lordotic Curve

   Pronation causese increased pelvic tilt which causes increased lordotic curvature which causes more pressure on the disc which causes back pain.