Thomas G. Bobick

Lifting in stooped and kneeling postures: Effects on lifting capacity, metabolic costs, and electromyography of eight trunk muscles

Abstract Twelve healthy, experienced underground coal miners performed lifting capacity tests in stooped and kneeling postures using a modified psychophysical, procedure. Subjects adjusted weight in a lifting box to the maximum they could handle without undue fatigue in an asymmetric lifting task. Lifting periods were 20 min in duration and the frequency was 10 lifts/min. Tests were performed under a 48-in. roof that restricted the subjects posture. Psychophysical, physiological, and biomechanical dependent measures included the maximum acceptable weight of lift (MAWL), heart rate (HR), rate of oxygen consumption (VO 2 ), ventilation volume rate (V E ), respiratory exchange ratio (R), and integrated electromyography (EMG) of eight trunk muscles. Results indicated that the MAWL was significantly lower when kneeling than when stooped (p 2 (p

Risks of hand tool injury in U.S. underground mining from 1978 through 1983 part II: Metal-nonmetal mining

Abstract The underground metal-nonmetal (MNM) mining industry represents an environment that is significantly different from other underground mining environments. This paper reports the findings of an investigation of hand tool-related accidents in the underground MNM mining industry over a 6-year period (1978–1983). The sequence of injury components associated with the various hand tools are described. The study revealed that about 85% of all lost work days due to hand tool-related injuries are the result of accidents involving the jackleg drill or scaling bar. The sequences of injury components for these tools and the ergonomic implications associated with these sequences are discussed. Suggestions are given for further research to correct the problems described.

Reducing Manual Materials Handling in Underground Coal Mining with Mechanical-Assist Devices:

Historically, manual handling of materials has consistently accounted for over 25 pct of all industrial accidents. In underground coal mining, the situation is worse. Materials-handling accidents routinely account for 30 to 35 pct of all lost-time injuries. Research sponsored by the Bureau of Mines, U.S. Dept. of the Interior, and conducted by Essex/Canyon Research, Inc., developed and evaluated several mechanical-assist devices to reduce the manual effort and the corresponding risk of injury from handling supplies and equipment in underground coal mines. The prototype devices were supplied to cooperating coal mining companies for evaluation. On-site visits, task analyses, and interviews were used to evaluate the devices. Three of them performed exceptionally well and have shown promise for reducing the amount of manual lifting and handling required underground.

Physiological Responses And Subjective Discomfort Of Simulated Whole-Body Vibration From A Mobile Underground Mining Machine

The U.S. Bureau of Mines has developed an in-house facility to evaluate selected effects of whole-body vibration (WBV) levels experienced by underground mobile equipment operators. Vertical vibration data were collected from a coal haulage vehicle via a uniaxial accelerometer attached to the machine frame under the operators seat. Data were analyzed and processed so a computer-controlled platform could approximate the vibration signals. Eight men (35.5 yr ± 6.5 SD) participated in a pilot study to evaluate the effects of shock and WBV on heart rate (HR), blood pressure (BP), and subjective discomfort. Subjects were exposed to vibration for 30-min periods while seated in a typical seat (backrest angle at 90° or 130°) that was plain steel or modified with 2 in foam padding. Subjects repeated the same protocol on a separate day, without the vibration. Results indicated the vibration significantly increased the HR (p < 0.01), systolic BP, mean BP, the number of times subjects reported discomfort, and overall subjective discomfort rating (p < 0.05). When seated in the steel seat, the overall discomfort rating (p < 0.001) and the number of times discomfort was reported (p < 0.05) increased significantly. Seatback angle had no significant effect on any of the dependent measures.

Effects Of Posture On Back Strength And Lifting Capacity

The Bureau of Mines performed a pilot study examining the effects of posture on back strength and Maximum Acceptable Weight of Lift (MAWL) on six healthy male subjects (M = 32 years ± 4 SD). Six back strength measurements (3 static and 3 dynamic) were made while the subjects were kneeling and standing. In addition, these subjects (who were unaccustomed to lifting in these postures) volunteered to participate in a study of psychophysically determined MAWL in both postures. Results of the back strength tests showed a significantly lower peak torque per body weight output in kneeling versus standing back strength measurements for five out of six test comparisons (p < .05). Subjective estimates of lifting capacity in the kneeling posture were significantly lower than those for the stooped posture (p < .05). The results of tests of back strength and lifting capacity in these two postures provide useful information to consider in determining the physiological and psychophysical stresses imposed by these work postures.

Preliminary Recommendations for Handling and Lifting Materials in Underground Low-Coal Mines

The U.S. Bureau of Mines has developed preliminary recommendations for handling materials in low-seam coal mines in an effort to reduce the incidence and cost of low-back pain in underground coal mines. Three main approaches to reducing back injuries are discussed: a) research and development of task specific materials-handling hardware that would reduce the number of manual lifts in underground coal mines, b) examining the supply-handling systems currently in use at low-seam coal mines through task analysis, and c) examining the lifting capacity of low-seam coal miners in the restricted postures that must be used in underground mines. Bureau of Mines research findings and recommendations are presented and discussed.

Assessing Visibility from Underground Coal Mining Equipment

A task analytic approach was used to define information requirements and visual features which served as sources of information for operations of continuous miners, shuttle cars and scoops. Information requirements were prioritized and the location of visual features determined. From this analysis, visual attention locations, containing one or more important visual features, were identified. A procedure was developed for assessing whether operators in existing machines could be expected to see the visual attention locations. The procedure makes use of a Human Eye Reference Measurement Instrument (HERMI) designed for this project and an outside-in photographic procedure.