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Hum Factors. 2018 Mar;60(2):191-200. doi: 10.1177/0018720817742515. Epub 2017 Nov 21.

Effects of Gloves and Pulling Task on Achievable Downward Pull Forces on a Rung.

Author information

1
University of Pittsburgh, Pittsburgh, Pennsylvania.
2
University of Wisconsin-Milwaukee.
3
Medical University of South Carolina, Charleston.

Abstract

Objective We examined the impacts of pulling task (breakaway and pull-down tasks at different postures), glove use, and their interaction on achievable downward pull forces from a ladder rung. Background Posture, glove use, and the type of pulling task are known to affect the achievable forces. However, a gap in the literature exists regarding how these factors affect achievable downward pulling forces, which are relevant to recovery from a perturbation during ladder climbing. Methods Forty subjects completed four downward pulling tasks (breakaway force; pull force at maximum height, shoulder height, and a middle height), using three glove conditions with varying coefficient of friction (COF) levels (cotton glove, low COF; bare hand, moderate COF; and latex-coated glove, high COF) with their dominant and nondominant hand. The outcome variable was the maximum force normalized to body weight. Results The highest forces were observed for the highest hand postures (breakaway and maximum height). Increased COF led to higher forces and had a larger effect on breakaway force than the other tasks. The dominant hand was associated with higher forces than the nondominant hand. Male subjects generated greater forces than female subjects, particularly for higher hand positions. Conclusion This study suggests that a higher hand position on the ladder, while avoiding low-friction gloves, may be effective for improving recovery from ladder perturbations. Application This study may guide preferred climbing strategies (particularly those that lead to a higher hand position) for improving recovery from a perturbation during ladder climbing.

KEYWORDS:

biomechanics; falls; hand forces; ladder climbing; pull strength

PMID:
29161154
DOI:
10.1177/0018720817742515

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