THE UPPER EXTREMITY ATTENUATES INTERMEDIATE-FREQUENCY VIBRATIONS

Vibration is related to reports of low back pain; however the biomecha nics of vibration transmission through the hand-arm system has not bee n previously studied. Vibration was recorded on an accelerometer mount ed to a pin percutaneously imbedded in the spinous process of L4 of fi ve human subjects. The energy was applied through an impact via a pend ulum. The subjects adopted an erect, relaxed or bent knee posture. The first resonance was 4-6 Hz and the second at 9-14 Hz. With the knee b ent, the signal was almost completely attenuated. If the impact was ap plied through a handle and the hand-arm system there was complete atte nuation. Copyright (C) 1996 Elsevier Science Ltd.