Does hard work prevent disc protrusion?

This study compares the prevalence of coal miners attending hospital with three defined back pain syndromes, with the number of miners in the working population. Of the men who attended hospital with back pain there were more miners than would be expected (2·78% of the miners compared with 1·99% of the non-miners). 0·32% of the miners had criteria of disc protrusion compared with 0·4% of non-miners; significantly more had syndromes associated with degenerative change. Relatively few men requiring disc excision were miners, whilst there were many who had decompressive surgery. This is compatible with the concept that heavy manual work strengthens the spine, restraining encroachment of a disc protrusion into the vertebral canal.