Biomechanical Evaluation of Three Post-Kneeling Tasks: Sitting, Walking, and Standing

Abstract

There are several occupations that require prolonged kneeling as part of their daily practice. Employees who kneel for a prolonged period of time have been reported to have high rates of knee and low back musculoskeletal disorders (Coggon et al. 2000, Halmstrom et al. 1992, Harkness et al. 2003, Manninen et al. 2002). These disorders result in excessive worker’s compensation costs. Gallagher el al. (2009) looked at the low seam mining industry and found that companies spent the most on knee related injuries with $4.2 million and $2.7 million for low back injuries. There is a lack of knowledge available as to what workers should do after they kneel to facilitate recovery. This study is intended to fill the gap in the knowledge base regarding recovery from extended kneeling using three different post-kneeling tasks. The main goal of this study was to compare three different post-kneeling tasks (sit, walk, and stand) and identify which of these tasks was the most effective at promoting recovery to pre-kneeling conditions. Nineteen subjects participated in this study. Each subject performed three trials, one for each post-kneeling task, in a random order. Each trial consisted of three parts: pre-kneeling, kneeling, and post-kneeling. Throughout the trials muscle oxygenation and muscle activity were recorded; while range of motion was collected before kneeling and after performing the post-kneeling task. For each variable survival analysis was performed to determine statistically significant differences. The results revealed that the limiting bio-marker for time to return to pre-kneeling baseline values is muscle oxygenation. Overall the walking and sitting post-kneeling tasks resulted in shorter times to return to pre-kneeling baseline values. However walking poses additional risks depending on the environment in which the workers are performing their tasks. Therefore the task recommended to perform after kneeling will depend on the surroundings and the job the worker has to perform following the kneeling task.