Introduction: Impaired muscle function due to pain or inactivity may contribute to poor outcome following disc surgery. This study investigated the effects of postoperative exercise on pain, disability and spinal function in patients undergoing microdiscectomy.

Methods: Volunteers who gave informed consent (65M/26F) were blindly randomised to Exercise and Control groups. All patients were assessed the week before surgery. Posture and range of motion were measured using the 3-Space Fastrak, and back muscle fatigue was evaluated during the Biering-Sorensen test from changes in median frequency of the electromyographic signal. In 42 patients, intra-operative muscle biopsies were obtained. Four weeks after surgery, patients underwent a second functional assessment, after which the Exercise group began a 4-week exercise programme. Further assessments were performed at 2, 6, 12, 18 and 24 months after surgery. Pain, disability and psychological status were evaluated throughout using appropriate questionnaires.

Results: Marked type II fibre atrophy was evident at surgery, and this was reflected in pre-operative measures of median frequency. At 4 weeks, both groups showed significant improvements in pain, disability and psychological status but limited improvements in function. At 2 months, the Exercise group showed further improvements in pain, disability and psychological status, increased ranges of motion, and improved fatigability. Increases in initial median frequency in the fatigue test suggested fibre hypertrophy. Further improvements in the Control group generally achieved significance 6–12 months after surgery.

Conclusions: Surgery is effective in improving pain, disability and psychological status. Recovery of muscle function after surgery is naturally slow but can be accelerated by post-operative exercise.