Iran Occupational Health

Background and aims: Whole-body vibration is one of the major factors that cause human discomfort and physiological reactions in industrial environments or vehicles. This study aimed in a laboratory environment to investigate the effect of whole body vibration on   human discomfort, heart rate and reaction time in men 20 to 30 years old.

 Methods:  40 Male students in Tehran University of Medical Sciences with     26.2± 1.7 years mean of age are participated in this study. All of participants were studied in   4 stages for 20 minutes in four vibration accelerations in x, y and z axis and frequency of 3 to7 Hz including without vibration, 0.56 m/s², 0.9 m/s² and 1.25 m/s² that was produced with vibration simulator. At each stage, a computerized visual reaction time test was taken and reaction times were measured for test and their Heart rate was also recorded using pulse oximetry. At the end of each stage the subjects were given 15 minutes to rest and their discomfort was rated during this time.

Results:  The results of this study showed that with increasing whole body vibration acceleration, discomfort rate (P<0.001) increase significantly. Also with increasing whole body vibration acceleration, heart rate (P<0.001) and reaction time (P<0.001) increase significantly.

Conclusion: The results showed that whole body vibration is a factor that affects human physiological and subjective functions. Hence, attending to level of vibration transmitted to human in vibrant environments have an important role in decreasing human discomfort and reducing reaction time in quick and sensitive activities.