Botulinum Toxin Versus Active Strength Training in the Treatment of Lateral Epicondylitis

Inclusion Criteria: * pain at the lateral side of the elbow over 3 months * local tenderness on palpation over the lateral epicondyle * positive Mill's sign * lateral elbow pain progression on resisted wrist and/or middle finger extension * involved in working life Exclusion Criteria: * bilateral symptoms or simultaneous medial epicondylitis * verified or suspected cervical radiculopathy or affected limb neuropathy * congenital or acquired deformities of the elbow * previous surgery of the elbow * infection, dislocation, tendon ruptures, or fractures in the area * systemic musculoskeletal or neurological disorders, incl. rheumatic diseases and fibromyalgia * allergy, antibodies or other contraindications for botulinum toxin * severe depression, chronic pain syndrome or somatisation disorder * ongoing retirement process * pregnancy or breastfeeding * current participation in other clinical trials