Diminished dynamic performance capacity of back and abdominal muscles in concrete reinforcement workers.

The dynamic performance capacity of back and straight abdominal muscles was clinically examined in 295 male, Finnish concrete reinforcement workers aged 19 to 64 years and engaged in heavy physical wonk including prolonged stooping. In 24% of the men both back and straight abdominal muscle performance capacity was reduced, in 18% only the capacity of the straight abdominal muscles, and in 4% only the performance of the back muscle. The prevalence of diminished trunk muscle performance capacity increased rapidly with age. Diminished back muscle, performance capacity was associated with a history of sciatica (X^2=16.9, p＜0.001) and diminished performance capacity of the straight abdominal muscles with a history of lumbago (X^2=5.9, p＜0.02) after adjustment for age. Diminished back muscle performance was associated with backache (X^2=16.9, p＜0.001) and sharp pain in the back (X^2=4.5, p＜0.05) during an ordinary workday, as was a1so diminished performance of the straight abdominal muscles (X^2=23.8, p＜0.001 and X^2=7.3, p＜0.01, respectively). No association between length of exposure to the back loads in reinforcement work and the prevalence of diminished trunk muscle performance capacity could be established.