Customer: Should you always sit with your knees way above your hips? Many cars are like this.
C.C. (Colm Campbell): Sitting with knees too far above the hips reduces the angle between the spine and thighs. Anything below ninety degrees puts tremendous stress on the lower spine and can tweak the sciatic resulting in pain which, in my own personal experience, is even greater than back pain. You mentioned car seats. They are well engineered with all sorts of clever adjustments. But they totally neglect the seat’s main function. To support the spine in good posture. Almost all car seats appear to be designed to make sure drivers sit in the C position. And the whole thing is compounded when using the clutch and brake. Pressing on the pedals transmits large forces up the legs to the lumbar spine.