Adverse effects of whole-body vibration on gastric motility.

To investigate the response of gastric motility to whole-body vibration (WBV) exposure, electrogastrography (EGG) and gastric manometry were performed in 10 healthy male volunteers. Sinusoidal vertical vibration of three different frequencies (4 Hz, 8 Hz, and 16 Hz) with a constant vibration magnitude of 1.0 ms-2 (rms.) was randomly given to the subject seated on the platform of a vibrator for 10 min. Exposure to vibration of 4 and 8 Hz decreased the amplitude of EGG wave and of the power spectrum corresponding to a slow wave component at fasting state. Food intake (solid meal 80 g, 135 cm3, 400 kcal) enhanced gastric motility showing about 2.5-fold in the power spectrum, of which response modes during and after vibration exposure were similar to those at fasting state. The periodical manometric change around one cpm was observed during vibration exposure under the condition of food intake. Short-term exposure to WBV led to a suppression of the activity of gastric smooth muscles and affect contraction wave. These responses may result from resonance of vibration frequency as a mechanical factor and stomach contents, and increase regulation of neurohumoral factors due to vibration stress.