In this Article
Supporting Research...
Jewel Warehouse Study Summary
Dr. Steven Lavender, a certified ergonomist and researcher at Rush Presbyterian St. Luke's Lifting Lab, conducted a preliminary study of The LiftTrainer™ Protocol to:
Quantify the change in the spine moments that can be achieved through training in safe lifting techniques in experienced warehouse employees over the course of a 30 minute session with The LiftTrainer™ system,
Assess the retention of lifting techniques at least one week after initial training, and to
Obtain feedback on the product from employees, supervisors, and facility management.
Eighteen subjects, who were employed as order pickers (assemblers) within the facility participated in the study. Their normal job requires extensive lifting as their primary responsibility is to palletize store orders from warehoused products. Each received a 30 minute training session following the protocol.
The tables shown here describe the magnitude of the spine moments before and after the biofeedback training.
A repeated measures analysis of variance indicated the differences between the mean of the initial set of lifts and the mean from the final set of lifts were significantly different for each moment direction (p<.05).
The tables show that percentage wise the largest improvement was observed in the lateral bending moments (38 percent) followed by the twisting moments (21 percent).
Overall, average drop in the spine moments was approximately 23 percent.
Five employees from the original sample were recruited to come back for a second training session scheduled between 8 and 10 days after the first training session. The training protocol was essentially repeated for these individuals. During the initial set of lifts in the second session, no instructions were given as to the lifting technique that should be used. The employees were only told to move the five boxes and reminded of the task scenario. Following this initial set of lifts, the tone was turned on and more coaching was provided. Typically, the employees were coached on continuing their foot work while increasing their lifting speed.
Overall, retention 8 to 10 days later was good. The tables below show the average forward bending, twisting, and side bending moments for the five employees participating in the second training session. The following points summarize the observations from these tables.
With the exception of the forward bending stress (moments) for the first employee, all of the data from the initial sets during the second session were less than that observed during the initial set in the first session.
The forward bending stresses (moments) from four employees and the twisting stresses (moments) from three employees were essentially unchanged between the final set of lifts in the first session and the initial set lifts in the second session, thereby suggesting that the concepts and behaviors had been retained.
While the lateral bending stresses measured during the initial set of lifts in the second session were always less than those measured during the initial set in the first session, they were greater than the lateral bending stresses measured during the final set of lifts in the first session. Continued training, however, reduced the side bending stress in the second session for 3 out of the 4 employees for whom data were available.
In summary, the data from this pilot test indicate that moments can be significantly reduced within a training session. Informal employee feedback indicated that The LiftTrainer™ helped motivate employees to learn ways to limit the "stress" on their spine while lifting. The biofeedback tone was shown to be useful at focussing the employees attention on the parts of the lifting and lowering cycle in which the moments peaked. Data collected 8 to 10 days after the initial training session shows retention of concepts and behavioral adaptations.
NIOSH Study Grant
In September, the National Institute for Occupational Safety and Health, after a peer review for scientific merit by its Study Section, announced a grant to Rush Presbyterian St. Luke's Medical Center to conduct a three year, controlled study of The LiftTrainer™ Protocol. The study abstract follows:
"The purpose of the study is to demonstrate the effectiveness of an aggressive new intervention for training and maintaining lifting techniques. The proposed project will use a new tool, The LiftTrainerÔ , developed by Innovative Sports Training. The tool, using a 3-dimensional motion tracking system, computes the instantaneous three dimensional dynamic spine moments and provides an audible biofeedback signal proportional to the magnitude of the stress. The emphasis here is on combining biomechanical analysis and concepts from learning theory in a protocol focussed on changing lifting behavior and quantifying the extent to which behavior is modified. Workers performing simulated job tasks are coached in one on one training sessions of 30 minute duration in how to minimize their spine moments while maintaining an acceptable task performance speed. Moment data gathered at the beginning and end of a session are used to quantify improvement within a session and retention between sessions. Behavior is maintained through the incorporation of reinforcement techniques borrowed from behavioral based safety programs and repeated training.
The aims of this project are: (1) to validate that lifting behaviors and the resulting spine moments can be modified in workers who perform repetitive material handling jobs (warehousing and distribution) as suggested by our pilot study, and (2) to determine the extent to which injury rates can be controlled through an aggressive training approach. In this study over 2400 employees from multiple facilities will be randomly assigned to receive training with The LiftTrainer™ or to view a back education video. The LiftTrainer™ protocol requires that each assigned employee participate in two sessions initially. Based on performance and retention levels after two sessions, employees needing additional training will be identified and retrained. All employees in The LiftTrainer™ group will receive an additional 3 training sessions scheduled on a quarterly basis. These employees will be assigned to self-reinforcing teams established within each facility. The primary dependent measures include: quarterly injury rates. turnover rates, absenteeism, and lost time rates for each study group In addition, within and between session changes in spine moments obtained for The LiftTrainer™ group will be tracked to determine how much change can be anticipated in the spine moments through training and the degree to which the changes are retained over time."
Supporting Studies for The LiftTrainer Protocol
The LiftTrainer™ Protocol draws on biomechanics and learning theory as the basis for providing a superior training tool. There are a number of studies which support the use of objective measurement, biofeedback, coaching and peer team reinforcement as a mechanism to effect behavior. These are sources which guided the development efforts and are followed with a brief description of the study significance for The LiftTrainer™ Protocol:
Barker KL, Atha J (1994). Reducing the biomechanical stress of lifting by training. Applied Ergonomics, 25, 373-378.
Daltroy, LH, Iversen, M.D., Larson, M.G., Lew, R., Wright, E., Ryan, J., Zwerling C., Fossel, A.H., Liang, M.H. (1997). A controlled trial of an educational program to prevent low back injuries. The New England Journal of Medicine, 337, 322-328.
De Looze MP, Toussaint HM, Ensink J, Mangnus C, Van Der Beek AJ (1994). The validity of visual observation to assess posture in a laboratory-simulated, manual material handling task. Ergonomics, 1335-1343.
Hall AR, Mason ID (1986). L’evaluation du role dune formation kinetique dans Ia prevention des accidents de manutention. Le Travail Humain, 49, 195-207.
Kernodle MW, Carlton LG (1992). Information feedback and the learning of multipledegree-of freedom activities. J. of Motor Behavior. 24,187-196.
Komaki J., Barwick KD, Scott LR (1978). A behavioral approach to occupational safety: pinpointing and reinforcing safe performance in a food manufacturing plant. J. of Applied Psychology, 63, 434-445.
Komaki J, Heinzmann AT, Lawson L (1980). Effect of training and feedback: Component analysis of a behavioral safety program J. of Applied Psychology, 65,261-270.
Magill RA, Schoenfelder-Zohd B (1996). A visual model and knowledge of performance as sources of information for learning a rhythmic gymnastics skill. International J. of Sport Psychology, 27, 7-22.
Stubbs DA, Buckle PW, Hudson MP, Rivers PM (1983). Back pain in the nursing profession II. The effectiveness of training. Ergonomics, 26, 767-779.
St. Vincent M, Tellier C, Lortie M (1989). Training in handling: an evaluative study. Ergonomics, 32,121-210.
Wood DJ (1987). Design and evaluation of back injury prevention program within a geriatric hospital. Spine, 12, 77-82.
Analysis of lifting techniques is a complex endeavor that is prone to error when analyzed subjectively. De Looze et al. (1994) demonstrated that trained observers, when compared to video analysis tools, failed to properly identify and categorize body mechanics during the simplest of forward lifts. This suggest that even if the student is given an opportunity to practice in front of the instructor, the instructor may not detect significant flaws in the demonstrated lifting technique. Moreover, Hall and Mason (1986), as reported by St. Vincent et al. (1989), showed that only 10 percent of a group of prospective trainers, after a week of training in how to teach lifting techniques, could perform all the movements taught correctly. Thus, the validity of what is demonstrated can be questionable.
Clearly, objective data must be the basis for training rather than subjective visual assessment. Objective data is necessary in order (1) to validate the methods taught for each individual, and (2) to determine whether a positive behavioral change has in fact occurred. Stubbs et al. (1983) used intra-abdominal pressure to quantify the biomechanical stress associated with patient handling. Barker and Atha (1994) measured improvements in lifting performance, spine compressive force, and ratings of perceived exertion. Each employee participating in a training process will likely be asked to change some aspect of their lifting behavior. Objective data showing not just behavioral change, but improvement in the biomechanical consequences of the change, are necessary to document learning and validate what is taught to the employee.
Lifting needs to be thought of and taught as a complex motor skill. Demonstrations and a few practice lifts in front of an instructor can not insure a beneficial behavioral change. Daltroy et al. (1997) noted that the employees understood the concepts covered in the instruction but failed to change their lifting behavior. Given that there was no behavioral change, the lack of injury reduction due to the training program should not be surprising. It has been shown, for example, that observing a model does little to improve performance on a gymnastics skill (Magill and SchoenfelderZohd, 1996).
Research also suggests that complex motor skills are best learned through a coaching and feedback process rather than demonstrations. Kernodle and Carlton (1992) in their study of throwing behavior found that performance was enhanced when subjects were provided feedback as to specific attributes of their movement associated with task performance. Performance was even more enhanced when coaching (a "transitional cue") was provided to direct the subjects towards improved performance. The employees in the geriatric facility analyzed by Wood (1987) responded favorably to having a physiotherapist coach them on lifting techniques on the job. Barker and Atha (1994) reported that an interactive lifting instruction session with a personal tutor resulted in significantly improved lifting practices than a control group, and lower ratings of perceived exertion and predicted compressive force.
Finally, the training process must contain a reinforcement mechanism. Most training programs are initiated without a means to reinforce the desired behavior once it had been trained. In the case of Komaki et al. the behaviors were only maintained when there was supervisory reinforcement. Komaki reported that simple feedback can be a powerful reinforcer. Following a training program to improve worker safety, observations were used to determine the percentage of operations performed safely and charted each week for all to see. Additionally, supervisors were made responsible for reinforcing safe behavior through positive feedback comments. In a later study Komaki et al. (1980) isolated the impact of the training versus the feedback. It was shown that while training on safety practices had a positive effect, the gains were much larger once the feedback was instituted.
Last Updated 1/1/04