Biomechanical evaluation of heavy tool-handling in two age groups of firemen.

The biomechanical load of a rescue-clearing task (lifting a power saw from the floor up to the ceiling level) was evaluated with six older (47 +/- 5 years) and seven younger firemen (32 +/- 2 years). The mean dynamic compressive force at the L5/SI disc was 5998 N for the older subjects and 6392 N for the younger subjects. The peak torques for the back and knee extensions were about equal for the two groups of the subjects. The younger subjects had a significantly higher movement speed in the knee extension than the older subjects (89.1 +/- 25.7 vs. 35.3 +/- 11.5 degrees/s, p less than 0.001). The results showed that lifting a power saw produced a high load on the musculoskeletal system, and that the load was not influenced by age.