Biomechanical Aspects of Fixed Ladder Climbing: Style, Ladder Tilt and Carrying

Abstract

This study aims to understand the effects of climbing style (hands on rungs vs. hands on rails), ladder pitch and bank, and carrying objects on hand and foot forces. An instrumented ladder was constructed to OSHA 1910.27 Fixed Ladder Standards. Hand and foot forces were recorded for six male and six female subjects as they ascended and descended the ladder. Although significant inter and intra subject climbing styles were observed for rung and rail climbing, it is still possible to draw important conclusions about the effects of climbing style, ladder pitch and bank, and carrying objects up and down ladders. Most of the work to ascend and descend the ladder is performed with the lower limbs. The hands must constantly exert force to prevent falling from a vertical ladder. Less hand force was exerted on the rails than on the rungs. Hand placement during rung climbing is constrained by rung spacing, while hand placement during rail climbing is determined by climber preference. It can be shown that required hand force is related to vertical hand placement and body center of mass position. Even though less resultant hand force was exerted during rail climb, the lateral component of hand force was greater for rail climbing than for rung climbing. Lateral hand forces may tend to destabilize the climber from the center of the ladder. Tilting the ladder forward reduces hand forces, which is consistent with the biomechanics of climbing and with previous studies. Tilting the ladder laterally did not significantly affect peak hand and foot forces, but it did affect the observed load/unload cycle time for hand and foot climbing movements.