The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks

Abstract

BackgroundTo determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models.MethodsTen male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads.ResultsPeak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences ≥80%.ConclusionBased on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.

System Dynamics Model Application for Ergonomic Assessment of Manual Material Handling Tasks

“…Thus the quantitative assessment of exerted forces on body joints is essential in reducing the risks of musculoskeletal disorders. While the lifting speed has been found to have significant impact on peak back compressive force (Greenland et al, 2013), this study focused on using Kinect-based motion capture data to include the forces generated by acceleration of body segment's movement during the operation. The studied operation starts with bending forward to reach the load, and then dynamic symmetric lifting with load in hands (male participant were asked to act freely in normal speed) ,and at the end holding the load (a box of 17lb) close to body in upright posture.…”

“…FC (L5-S1) = Σ (FEXT + FUB + FL + FUA + FLA + FHN) -FAB Where FEXT is the lower-back extensor muscle force and FL, FUB, FUA, FLA, FHN are the components of force due to the load, upper-back, upper-arm, lower-arm, and head and neck, respectively. According to the study by (Greenland et al,2013), each force component could be calculated based on Newton's second law of motion which includes the mass of the load and body segment multiplied by acceleration of movement. There is a general agreement that by considering additional forces generated during acceleration of the body segment's centre of mass and load, greater accuracy in predicting the magnitude of BCF on spine can be achieved (Bazrgari et al, 2009).…”

“…Its been shown that dynamic calculation is superior to corresponding static calculations for predicting back compressive force (BCF) and as a result this study focus on dynamic biomechanical systems. While static calculations at any speed would yield the same results for BCF, dynamic calculation has been found to yield higher peak value of BCF for fast lifting spped (Greenland et al, 2013). System dynamics (SD) method as a modeling and analyzing tool is suitable for any dynamic system characterized by mutual interactions, information feedback, and interdependencies among variables.…”

Investigation of the Lifting Speed on Lumber Muscles Activities

“…It is also observed that the motor control system is independent of the variation of the load rate, but it depends on the various lifting speeds [12]. Furthermore, a previous study revealed that the low speed lifting can be dangerous as much as the high speed lifting [13]. In addition, the lifting speed, which is a risk factor for LBP [14][15][16], is one of the important factors that can affect the electrical activity of the erector spinae muscles [17].…”

Experimental investigation and model-based simulation on lifting biomechanics : an emphasis on age effects

“…The result showed that, the angular accelerations of all lumbar vertebrae (L2-L5) at the early phase of lifting were higher in highvelocity lifting trials, which might induce higher spinal loads. Greenland et al (2013) examined the effects of lifting velocity on cumulative and peak low back loads during symmetric lifting. In the experiment, participants lifted loads of two different weights (2.25 and 9 kg) at three different velocities (0.34, 0.44 and 0.64 m/s).…”