Mechanical lifting energy consumption in work activities designed by means of the "revised NIOSH lifting equation".

The aims of the present work were: to calculate lifting energy consumption (LEC) in work activities designed to have a growing lifting index (LI) by means of revised NIOSH lifting equation; to evaluate the relationship between LEC and forces at the L ₅ -S ₁ joint. The kinematic and kinetic data of 20 workers were recorded during the execution of lifting tasks in three conditions. We computed kinetic, potential and mechanical energy and the corresponding LEC by considering three different centers of mass of: 1) the load (CoM _L ); 2) the multi-segment upper body model and load together (CoM _Upp+L ); 3) the whole body and load together (CoM _Tot ). We also estimated compression and shear forces. Results shows that LEC calculated for CoM _Upp+L and CoM _Tot grew significantly with the LI and that all the lifting condition pairs are discriminated. The correlation analysis highlighted a relationship between LEC and forces that determine injuries at the L ₅ -S ₁ joint.