Mining Publication: 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 degrees or 130 degrees) 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.