Sa. Lavender et Ws. Marras, THE EFFECTS OF A TEMPORAL WARNING SIGNAL ON THE BIOMECHANICAL PREPARATIONS FOR SUDDEN LOADING, Journal of electromyography and kinesiology, 5(1), 1995, pp. 45-56
An experiment was performed to evaluate the biomechanical preparations
exhibited in anticipation of sudden loading. Four experienced subject
s received sudden loads at 1 min intervals. An analogue display was us
ed to convey the time remaining in the 1 min intervals. The dependent
measures included the electromyographic (EMG) data obtained from eight
trunk muscles and the changes in body posture. These data were compar
ed with data from a baseline session in which no timing display was av
ailable. In both sessions, when loads were anticipated the back muscle
s were tensed. However, with the timing display available there was an
alteration in the preparatory co-contraction of the trunk muscles. Th
e change in co-contraction was primarily due to the increased torque g
enerated by the erector spinae (ES) as opposed to a decrease in the to
rque generated by the anterior muscles. This indicated that there was
less stiffening of the torso during preparation when temporal informat
ion was available. During the sudden loading three of the four subject
s reduced the peak compressive forces on the spine predicted via an EM
G driven model while maintaining consistent levels of trunk stability.