[The role of coactivation of the trunk musculature in evaluating biomechanical risk].

One of the mechanisms adopted by the central nervous system to stabilize the joints or the spine is muscle co-activation. Nevertheless during lifting tasks muscle co-activation increases spinal load. For co-activation assessment during 3 lifting tasks at increasing load levels we utilized a time-varying co-activation algorithm proposed by Rudolph in 2000. We found that Rudolph co-activation index grew with lifting index. The time-varying co-activation index gave a continuous measure of low back compression. A time-varying co-activation index could be of great interest in all conditions in which NIOSH equation is not applicable.