Faster relief from runner's sciatica

A sensation of electric shocks, pain in the buttock that radiates down the leg - the symptoms are very similar to those of sciatica, yet the diagnosis is often difficult to make.
In athletes, particularly runners, these disturbances are mainly linked to piriformis syndrome, also known as runner's sciatica.
What are the causes of this disabling condition, how can it be relieved and how can you get back to training without pain? We've got the answers!