ABSTRACT
The purpose of this study was to compare the effects of high-frequency vibration when applied to two areas of different size. Subjects were 30 right-handed Caucasian women, aged 19-38 years, with a negative history of upper extremity dysfunction. The experimental cutaneous pain threshold was determined by stimulating the skin over the pisiform bone on the palmar surface of the hand. Pain threshold measurements were taken before, during, and 2 and 5 min after vibration. Group A received vibration to an area 12.5 cm2 on the ulnar aspect of the palm of the hand 1 cm distal to the pisiform bone. Group B received vibration to an area 25 cm2, also on the ulnar aspect of the palm of the hand. Results of the mixed design analysis of variance performed on the mean pain thresholds indicate that there was no significant main effect for group (size of area vibrated), p greater than 0.05, or interaction effect between group by trial (size of area vibrated and time of pain threshold measurement), p greater than 0.05. There was a significant main effect for trial (time of pain threshold measurement), p less than 0.001. Pain threshold values were greatest for both groups during the period of vibration.
