TY - JOUR

T1 - The error of L5/S1 joint moment calculation in a body-centered non-inertial reference frame when the fictitious force is ignored

AU - Xu, X.

AU - Faber, G.S.

AU - Kingma, I.

AU - Chang, C.C.

AU - Hsiang, S.M.

PY - 2013

Y1 - 2013

N2 - In ergonomics studies, linked segment models are commonly used for estimating dynamic L5/S1 joint moments during lifting tasks. The kinematics data input to these models are with respect to an arbitrary stationary reference frame. However, a body-centered reference frame, which is defined using the position and the orientation of human body segments, is sometimes used to conveniently identify the location of the load relative to the body. When a body-centered reference frame is moving with the body, it is a non-inertial reference frame and fictitious force exists. Directly applying a linked segment model to the kinematics data with respect to a body-centered non-inertial reference frame will ignore the effect of this fictitious force and introduce errors during L5/S1 moment estimation. In the current study, various lifting tasks were performed in the laboratory environment. The L5/S1 joint moments during the lifting tasks were calculated by a linked segment model with respect to a stationary reference frame and to a body-centered non-inertial reference frame. The results indicate that applying a linked segment model with respect to a body-centered non-inertial reference frame will result in overestimating the peak L5/S1 joint moments of the coronal plane, sagittal plane, and transverse plane during lifting tasks by 78%, 2%, and 59% on average, respectively. The instant when the peak moment occurred was delayed by 0.13, 0.03, and 0.09. s on average, correspondingly for the three planes. The root-mean-square errors of the L5/S1 joint moment for the three planes are 21. Nm, 19. Nm, and 9. Nm, correspondingly. © 2013 Elsevier Ltd.

AB - In ergonomics studies, linked segment models are commonly used for estimating dynamic L5/S1 joint moments during lifting tasks. The kinematics data input to these models are with respect to an arbitrary stationary reference frame. However, a body-centered reference frame, which is defined using the position and the orientation of human body segments, is sometimes used to conveniently identify the location of the load relative to the body. When a body-centered reference frame is moving with the body, it is a non-inertial reference frame and fictitious force exists. Directly applying a linked segment model to the kinematics data with respect to a body-centered non-inertial reference frame will ignore the effect of this fictitious force and introduce errors during L5/S1 moment estimation. In the current study, various lifting tasks were performed in the laboratory environment. The L5/S1 joint moments during the lifting tasks were calculated by a linked segment model with respect to a stationary reference frame and to a body-centered non-inertial reference frame. The results indicate that applying a linked segment model with respect to a body-centered non-inertial reference frame will result in overestimating the peak L5/S1 joint moments of the coronal plane, sagittal plane, and transverse plane during lifting tasks by 78%, 2%, and 59% on average, respectively. The instant when the peak moment occurred was delayed by 0.13, 0.03, and 0.09. s on average, correspondingly for the three planes. The root-mean-square errors of the L5/S1 joint moment for the three planes are 21. Nm, 19. Nm, and 9. Nm, correspondingly. © 2013 Elsevier Ltd.

U2 - 10.1016/j.jbiomech.2013.05.012

DO - 10.1016/j.jbiomech.2013.05.012

M3 - Article

VL - 2013

SP - 1943

EP - 1947

JO - Journal of Biomechanics

JF - Journal of Biomechanics

SN - 0021-9290

IS - 46

ER -