Effects of asymmetrical stance and movement on body rotation in pushing

Abstract

Pushing objects in the presence of body asymmetries could increase the risk of back injury. Furthermore, when the object is heavy, it could exacerbate the effects induced by asymmetrical posture. We investigated how the use of asymmetrical posture and/or upper extremity movement affect vertical torque (Tz) and center of pressure (COP) displacement during pushing. Ten healthy volunteers were instructed to push objects of three different weights using two hands (symmetrical hand use) or one hand (asymmetrical hand use) while standing in symmetrical or asymmetrical foot-positions. The peak values of Tz and COP displacement in the medial-lateral direction (COPML) were analyzed. In cases of isolated asymmetry, changes in the Tz were mainly linked with effects of hand-use whereas effects of foot-position dominated changes in the COPML displacement. In cases of a combined asymmetry, the magnitudes of both Tz and COPML were additive when asymmetrical hand-use and foot-position induced the rotation of the lower and upper body in the same direction or subtractive when asymmetries resulted in the rotation of the body segments in the opposite directions. Moreover, larger Tz and COP displacements were seen when pushing the heavy weight. The results point out the importance of using Tz and COPML to describe the isolated or combined effects of asymmetrical upper extremity movement and asymmetrical posture on body rotation during pushing. Furthermore, it suggests that a proper combination of unilateral arm movement and foot placements could help to reduce body rotation even when pushing heavy objects.

Older adults utilize less efficient postural control when performing pushing task

“…Second, the increased COP displacement during the balance restoration phase after the pushing movement, combined with slow reaction time seen in older adults (Stelmach, Populin, 1990), might predispose them to even larger instability making it more difficult to regain balance. It was also demonstrated that when young subjects push heavier objects, they show increased magnitudes of COP displacement and vertical torque (Lee and Aruin, 2015). As such, one could suggest that when older adults are required to push heavier objects, their inability to control the COP magnitude and displacement might predispose them to losing their balance and potentially falling.…”

Baropodometric evaluation of foot load distribution during gait in the group of professionally active nurses

“…Approximately 25% of nurses declare that they always lift weights ergonomically, bending lower limbs and keeping the spine straight . Adoption of forced, asymmetrical body postures and a long‐standing position during work can affect the improper use of the feet through the asymmetry of the distribution of the load on the feet …”

“…5 Adoption of forced, asymmetrical body postures and a long-standing position during work can affect the improper use of the feet through the asymmetry of the distribution of the load on the feet. 16,17 Functional efficiency of the foot is determined by its musculoskeletal efficiency, bone structure and the loads it undergoes during everyday activity. The method of loading and setting of the foot is often the result of biomechanical relationships concerning other parts of the movement system.…”

Foot Position Measurement during Assistive Motion for Sit-to-Stand Using a Single Inertial Sensor and Shoe-Type Force Sensors

“…To address the aforementioned concerns, we have been developing a method for measuring foot position using a single inertial sensor on trunk and shoe-type force sensors [ 19 ]. Previous studies have shown that the use of an inertial sensor on the trunk and shoe-type force sensors can be considered an effective method for measuring foot position given the relationship between trunk movement and foot position during manual handling [ 9 , 20 , 21 , 22 , 23 ]. Wagner et al found that a wide-footed stance is related to trunk rotation during manual lifting tasks [ 20 ].…”