Biomechanical analysis in ladder climbing: the effect of slant angle and climbing speed.

This paper presents the findings of a study conducted to determine the peak forces generated in the articulated joints and the foot/floor contact point of a ladder while an individual was engaged in ladder climbing. A kinematic description of joint movements and the calculation of forces acting on each body segment as well as the foot of the ladder were obtained on the basis of videographic data. Task variations were (1) slant angle (70 degrees and 75 degrees with the horizontal) and (2) climbing speed (86 steps/min and 106 steps/min). It was identified in this study that the ladder's friction forces had a time variant nature as a result of biodynamic movements. There were two peak friction coefficients, in opposite directions, occurring at 7% and 38% of each half of the strike time. The primary differences between climbing the ladders at 70 and 75 degrees were a greater posterior displacement of the body's center gravity and smaller peak center gravity shearing forces in climbing the 75 degree ladder. There were greater posterior displacement of the center gravity of body and a larger biomechanical load while climbing at 106 steps/min than at 86 steps/min.