The Effects of Direction of Exertion, Path, and Load Placement in Nursing Cart Pushing and Pulling Tasks: An Electromyographical Study

Abstract

The purpose of this study was to explore the effects of direction of exertion (DOE) (pushing, pulling), path (walking in a straight line, turning left, walking uphill), and load placement (LP) (the 18 blocks were indicated by X, Y and Z axis; there were 3 levels on the X axis, 2 levels on the Y axis, and 3 levels on the Z axis) on muscle activity and ratings of perceived exertion in nursing cart pushing and pulling tasks. Ten participants who were female students and not experienced nurses were recruited to participate in the experiment. Each participant performed 108 experimental trials in the study, consisting of 2 directions of exertion (push and pull), 3 paths, and 18 load placements (indicated by X, Y and Z axes). A 23kg load was placed into one load placement. The dependent variables were electromyographic (EMG) data of four muscles collected bilaterally as follows: Left (L) and right (R) trapezius (TR), flexor digitorum superficialis (FDS), extensor digitorum (ED), and erector spinae (ES) and subjective ratings of perceived exertion (RPE). Split-split-plot ANOVA was conducted to analyze significant differences between DOE, path, and LP in the EMG and RPE data. Pulling cart tasks produced a significantly higher activation of the muscles (RTR:54.4%, LTR:50.3%, LFDS:57.0%, LED:63.4%, RES:40.7%, LES:36.7%) than pushing cart tasks (RTR:42.4%, LTR:35.1%, LFDS:32.3%, LED:55.1%, RES:33.3%, LES:32.1%). A significantly greater perceived exertion was found in pulling cart tasks than pushing cart tasks. Significantly higher activation of all muscles and perceived exertion were observed for walking uphill than walking in a straight line and turning left. Significantly lower muscle activity of all muscles and subject ratings were observed for the central position on the X axis, the bottom position on the Y axis, and the posterior position on the Z axis. These findings suggest that nursing staff should adopt forward pushing when moving a nursing cart, instead of backward pulling, and that uphill paths should be avoided in the design of work environments. In terms of distribution of the load in a nursing cart, heavier materials should be positioned at bottom of the cabinet, centered on the horizontal plane and close to the handle, to reduce the physical load of the nursing staff.

Human Body Mechanics of Pushing and Pulling: Analyzing the Factors of Task-related Strain on the Musculoskeletal System

“…In eight studies the handle was set at one or more fixed heights [9], [10], [12], [14], [26], [27], [28], [30].…”

“…One study [30] reported higher muscle activation in general for pulling medicine carts as opposed to pushing.…”

Safe Patient Handling and Movement

“…In addition to lifting objects, perioperative team members push and pull wheeled equipment. Research evidence shows that muscle activity is lower during pushing than pulling; therefore, perioperative team members should push wheeled equipment rather than pull it. To decrease risk of injury when moving wheeled equipment, perioperative staff members also should ensure…”

“…Occupational injuries associated with nursing frequently involve the musculoskeletal system; these injuries typically involve the lower back, shoulders, and upper extremities . Many of these injuries are a result of overuse and repetitive movements, including various physical stressors (eg, manual lifting, pulling, pushing, awkward, or static postures). The nature of the perioperative environment increases the possibility that health care workers will experience physical stressors.…”

The Effects of Ramp Gradients and Pushing–Pulling Techniques on Lumbar Spinal Load in Healthy Workers

“…These factors include speed of motion, load conditions, psychophysiological, force orientations, load magnitudes, work experience, hand force limits, handle height, interhandle distance, ramp gradients, and direction of exertion. In addition these are risk factors of work-related injuries [ 12 , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] ]. Many tasks in industrial and health-care settings are associated with pushing and pulling [ 9 ].…”