Effects of speed of lift on static and inertial moments at the joints

Biomechanical models, often in the form of static models, are used to quant ify stresses on the body. It has been shown that static models underestimat e the stresses of a dynamic activity since static models fail to account fo r inertial effects. The primary objective of this study was to determine th e effect of lifting speed on the reactive moments at the joints using sever al cumulative measures of whole-body stress. Five male subjects lifted a bo x loaded with weight based on their individual maximum acceptable weights o f lift at five speeds covering the range from very slow to very fast. When averaged across the lift, the inertial component accounted for 2.5%, 5.5%, 10%, 12% and 14% of the average dynamic moment at each of the five speeds, from slowest to fastest, respectively.