Body height changes from vibration.

A device for measuring body height is reported (SD, 1 mm). The change in body height before and after vibration and quiet sitting respectively was studied in eight men aged 22-44 years who were free of back pain. The vibration frequency was set at 5 Hz and the acceleration at 2 msec-2. Subjects were asked to report for testing within 2 hours after arising from bed. Body height was measured before and immediately after vibration or sitting exposure and the measurements were repeated at different intervals up to 2 hours after the experiment. Results show that exposure to vibration increases the overall creep response in most subjects. There is a great deal of variability in response between subjects, but most of them show a recovery to the average creep response within a 2-hour time interval.