| Ergonomics can be defined as the responsibility to ensure that the demands of a job do not exceed the capabilities of a worker (Garg, Chaffin, and Herrin, 1978). Evaluating physiological demands on workers, particularly individuals performing highly varied tasks or monitoring their work in the field, can be a complex problem. Using on-person sensors to record kinematic and physiological measurements throughout extended is one proposed method by which to collect data necessary to evaluate the demands placed on the workers. In order to assess the efficacy of the data that would be collected, it is critical to evaluate the intrusive effects of the on-person sensors on the manner in which the work is performed. For the purpose of this study, various outfit ensembles, consisting of combinations of Clo, Mass, and Banding, were analyzed in order to determine whether or not they affect the posture while individuals perform a repetitive lifting task. Thirty-two paid volunteers participated in this study. Each subject was randomly assigned one of eight experimental ensembles. VICON MX-13 near-infrared cameras were used to capture whole-body kinematics. Subjects were asked to perform a cyclic work protocol that consisted of six twenty-minute cycles, including five-minutes each of 30 ground-to-waist lifts and lowers, 30 standing arm lifts and lowers, continuous walking on a treadmill, and a rest period. A 23 factorial, between-subjects design was used, producing 8 experimental ensemble conditions for combinations of Clo, Mass, and Banding. Statistical analyses were performed with a stepwise regression and general linear model (GLM). The bilateral angles for the hips, knees, and ankles were the dependent variables; independent variables were Banding, Clo, Mass, Part, Phase, and Cycle. From the stepwise regression (alpha=0.10 to remove), Part and Phase were removed from the model. From the GLM, the adjusted R2 values indicated that a good fit existed between the variables in the model. ANOVA results indicated that the main effects and all interactions effects of the ensemble conditions were significant, but the significance varied across lower body joints. Results indicate that Banding and Clo have significant effects on posture, but their effects are less than the nominally fatiguing aspect of the tasks performed. As expected, adding mass to the subjects caused significant changes to their posture over time, suggesting elevated levels of fatigue. Future studies should include other populations, fitness and experience constraints, and tasks with a lower physiological burden. |
