Erika M Pliner1, N J Seo2, Viswanathan Ramakrishnan3, Kurt E Beschorner4. 1. Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53212, USA. Electronic address: emp95@pitt.edu. 2. Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53212, USA. Electronic address: seon@musc.edu. 3. Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53212, USA. Electronic address: ramakris@musc.edu. 4. Department of Industrial Engineering, University of Wisconsin-Milwaukee, Milwaukee, WI 53212, USA. Electronic address: beschorn@pitt.edu.
Abstract
BACKGROUND: A plurality of fatal falls to lower levels involve ladders. After a slip/misstep on a ladder, climbers use their upper and lower limbs to reestablish contact with the ladder. RESEARCH QUESTION: This study investigates the impact of upper body strength, hand placement and foot placement on fall severity after a ladder climbing perturbation. METHODS: Participants performed upper body strength tests (breakaway and grip strength) and climbed a vertical, fixed ladder while a misstep perturbation was applied under the foot. After the perturbation, three hand placement and two foot placement responses were generally observed. Common hand placement responses included the hand moving two rungs, one rung, or did not move to a different rung. Foot placement responses included at least one foot or no feet reestablished contact with the ladder rung(s). Fall severity was quantified by the peak harness force observed after the perturbation. RESULTS: Increased strength, reestablishing at least one foot on the ladder, and ascending (compared with descending) the ladder was associated with a reduction in fall severity. An interaction effect indicated that the impact of hand placement was altered by climbing direction. Moving the hand one rung during ascent and moving the hand two rungs during descent was associated with an increased fall severity. Cases where the hand decoupled from the ladder was associated with higher fall severity. Upper body strength assessed using a portable grip dynamometer was sufficient to predict fall severity. DISCUSSION: This study confirms the multifactor role of upper body strength, hand placement and foot placement in preventing falls from ladders. Furthermore, a portable dynamometer shows potential to screen for high-risk individuals. Results of this investigation may guide targeted interventions to prevent falls from ladders.
BACKGROUND: A plurality of fatal falls to lower levels involve ladders. After a slip/misstep on a ladder, climbers use their upper and lower limbs to reestablish contact with the ladder. RESEARCH QUESTION: This study investigates the impact of upper body strength, hand placement and foot placement on fall severity after a ladder climbing perturbation. METHODS:Participants performed upper body strength tests (breakaway and grip strength) and climbed a vertical, fixed ladder while a misstep perturbation was applied under the foot. After the perturbation, three hand placement and two foot placement responses were generally observed. Common hand placement responses included the hand moving two rungs, one rung, or did not move to a different rung. Foot placement responses included at least one foot or no feet reestablished contact with the ladder rung(s). Fall severity was quantified by the peak harness force observed after the perturbation. RESULTS: Increased strength, reestablishing at least one foot on the ladder, and ascending (compared with descending) the ladder was associated with a reduction in fall severity. An interaction effect indicated that the impact of hand placement was altered by climbing direction. Moving the hand one rung during ascent and moving the hand two rungs during descent was associated with an increased fall severity. Cases where the hand decoupled from the ladder was associated with higher fall severity. Upper body strength assessed using a portable grip dynamometer was sufficient to predict fall severity. DISCUSSION: This study confirms the multifactor role of upper body strength, hand placement and foot placement in preventing falls from ladders. Furthermore, a portable dynamometer shows potential to screen for high-risk individuals. Results of this investigation may guide targeted interventions to prevent falls from ladders.
Authors: Peter F Ehrlich; Justin G Young; Sheryl Ulin; Charles Woolley; Thomas J Armstrong; Andrzej Galecki; Shu Chen; James A Ashton-Miller Journal: Hum Factors Date: 2013-06 Impact factor: 2.888