Association between vasoconstriction during and following exposure to hand-transmitted vibration

Objectives This study investigated whether reductions in finger blood flow (FBF) during and after vibration are similarly dependent on the magnitude and duration of vibration. Methods FBF on the left and right hand was measured every minute during, and for 1 hour following, exposure of the right hand to one of three magnitudes of 125-Hz sinusoidal vibration (0, 22, or 88 ms 2 r.m.s.) for one of two durations (7.5 or 15 minutes). Each session comprised five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (7.5 or 15 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (60 minutes). Results Both magnitudes and durations of vibration reduced FBF in the exposed and unexposed hands, both during and after vibration. With increased magnitude of vibration, there was increased vasoconstriction in all fingers during and after exposure, and longer recovery times after vibration exposure. With increased duration of vibration, there were no changes in vascular responses during exposure but increased vasoconstriction after exposure and prolonged recovery times. With the higher vibration magnitude, the reduction in FBF during exposure was correlated with the time taken to recover after exposure. Conclusions Subjects with greater reduction in blood flow during vibration exposure also have stronger and longer vasoconstriction during subsequent recovery. The correlation between vascular changes during and after vibration exposure suggests similar mechanisms control FBF during and after vibration exposure.