Sciatica is a pain felt in the low back area (lumbars) that extends to the buttock area and even down the leg. The pain may be accompanied by numbness, altered sensation or even loss of strength in the leg.
The sciatic nerve is formed by the nerves of the lower lumbars and the upper three sacral nerves. Due to all the nerves involved in forming the sciatic nerve, it is not uncommon for one or more areas to become “pinched” or aggravated.
What causes the sciatic nerve to become irritated?

Poor postures
Accidents
Physical stress
Too many hours seated
Driving for long periods
Anatomical short leg
Long distant running with poor footwear
Heavy bags and/or backpacks