@article{reid_mirka_2007, title={Learning curve analysis of a patient lift-assist device}, volume={38}, ISSN={["0003-6870"]}, DOI={10.1016/j.apergo.2006.10.006}, abstractNote={One of the challenges facing ergonomists in the implementation of an ergonomic solution is addressing the concerns related to their impact on productivity. The focus of the current study was to (1) apply standard learning curve analysis to the learning that takes place as an individual works with a patient handling device and (2) compare the effects of two different training protocols on measures of learning. Eighteen subjects completed 11 replications of a patient transfer task after participating in either an "interactive" training protocol or "see-one-do-one" training protocol. The results show that the learning rate for this task was 83% with no difference as a function of training protocol. The results do indicate that the effect of Training Method was significant (p<0.05) for time to complete the first patient lift task (370s for the interactive training vs. 475s for see-one-do-one training). The results of the analysis of the survey data supported the objective results in that the only measure that was responsive to training type (p<0.05) was related to comfort level in performing the patient lift task for the first time. The results emphasize the importance in considering learning when introducing an intervention in the workplace, and showed that in this instance, training type had an immediate impact on productivity, but that this effect diminished over time.}, number={6}, journal={APPLIED ERGONOMICS}, author={Reid, Stephanie A. and Mirka, Gary A.}, year={2007}, month={Nov}, pages={765–771} }
 @article{jiang_shu_drum_reid_mirka_2006, title={Effects of age on muscle activity and upper body kinematics during a repetitive forearm supination task}, volume={36}, ISSN={["1872-8219"]}, DOI={10.1016/j.ergon.2006.07.008}, abstractNote={The principal objective of this study was to assess the effects of age on upper extremity muscle activation patterns and upper body kinematics during a forearm supination task. Age-related physiological and biomechanical changes in the musculoskeletal system have been documented in the literature. It was hypothesized that these changes may have an impact on muscle recruitment and work technique (postural/kinematic) employed during work tasks. A simple repetitive forearm supination task was used to evaluate these hypotheses. Twenty subjects (ten in each age group 19–29 and 55–65) performed a series of static and dynamic forearm supination tasks on a work simulator. These exertions were performed at eight different levels of supination torque: 5–40 lb-in in 5 lb-in increments. As the subjects performed the static exertions the activation levels of several key muscles of the upper extremity were captured using surface electromyography. As the subjects performed the dynamic exertions, the motions of the upper body and upper extremity were captured using a magnetic field-based motion analysis system. The results of the static exertions showed that older subjects generated 135% greater trapezius muscle activity (significant at p<0.05 level) but no other muscle group sampled showed a significant difference between the age groups. In the dynamic exertions, age had no effect on upper limb/torso kinematic responses. In both the static and dynamic exertions, supination torque level had a significant impact on muscle activity and kinematics. These results provide empirical evidence that age alone does not have a consistent impact on biomechanical responses during physically demanding work tasks.}, number={11}, journal={INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS}, author={Jiang, Zongliang and Shu, Yu and Drum, Jonathan and Reid, Stephanie and Mirka, Gary A.}, year={2006}, month={Nov}, pages={951–957} }
 @article{jiang_shin_freeman_reid_mirka_2005, title={A study of lifting tasks performed on laterally slanted ground surfaces}, volume={48}, ISSN={["0014-0139"]}, DOI={10.1080/00140130500123761}, abstractNote={Lifting in most industrial environments is performed on a smooth, level ground surface. There are, however, many outdoor work environments (e.g. agriculture and construction) that require manual material handling activities on variable grade ground surfaces. Quantifying the biomechanical response while lifting under these conditions may provide insight into the aetiology of lifting-related injury. The aim of the current study was to quantify the effect of laterally slanted ground surfaces on the biomechanical response. Ten subjects performed both isometric weight-holding tasks and dynamic lifting exertions (both using a 40% of max load) while standing on a platform that was laterally tilted at 0, 10, 20 and 30° from horizontal. As the subject performed the isometric exertions, the electromyographic (EMG) activity of trunk extensors and knee extensors were collected and during the dynamic lifting tasks the whole body kinematics were collected. The whole body kinematics data were used in a dynamic biomechanical model to calculate the time-dependent moment about L5/S1 and the time-dependent lateral forces acting on the body segments. The results of the isometric weight-holding task show a significant (p < 0.05) effect of slant angle on the normalized integrated EMG values in both the left (increase by 26%) and right (increase by 70%) trunk extensors, indicating a significant increase in the protective co-contraction response. The results of the dynamic lifting tasks revealed a consistent reduction in the peak dynamic L5/S1 moment (decreased by 9%) and an increase in the instability producing lateral forces (increased by 111%) with increasing slant angle. These results provide quantitative insight into the response of the human lifter under these adverse lifting conditions.}, number={7}, journal={ERGONOMICS}, author={Jiang, ZL and Shin, G and Freeman, J and Reid, S and Mirka, GA}, year={2005}, month={Jun}, pages={782–795} }