Laboratory-based whole-body vibration studies often involve complex experimental designs, dozens of vibration exposures and multiple sessions. Shortening the test vibration duration would increase experimental efficiency by permitting more trials in the same time period. This study evaluated reported discomfort based on different sinusoidal vibration durations and amounts of rest between successive vibrations. Ten subjects were exposed to four blocks of vibration trials (15/20 second vibration and 5/10 second rest durations). Each block of 37 trials included repeated single axis, planar, and 6 degree of freedom multi-axial vibrations. These repeated trials were analysed to evaluate whether discomfort varied between the different blocks. We did not observe any statistically significant differences in discomfort between the different vibration and rest durations. This finding is useful for designing future vibration experiments. Part II of this study evaluates the relationship between discomfort and vibration exposure.