The aim of this study is to compare two levels (high and low forces) of short term lumbar traction on pain and functional tests of the lower limbs in a specific population of patients presenting with acute lumbar sciatica secondary to disc herniation. The investigators hypothesize that, in this particular medical condition, high level of lumbar traction might be more effective than low level lumbar traction in decreasing the pain associated with acute sciatica.

Inclusion Criteria:

• less than 6-week lumbar sciatica secondary to disc herniation, confirmed by pain radiating down the leg along the distribution of the sciatic nerve together with positive straight leg raising test (SLRT)

Exclusion Criteria:

• symptoms persisting for more than 6 weeks
• signs of clinical neurological deficit
• lumbar sciatica not caused by disc herniation
• presence of lumbar tomodensitometry abnormalities
• Subjects younger than 18
• pregnant women
• patients on medical leave for more than 3 weeks at inclusion
• patients with history of lumbar surgery
• patients who already had lumbar traction therapy