You have several options! While on the VibraSonic, you can hold your most perfect posture. Shoulders back, head up looking forward, breathing deeply. Standing tall places your body posture in a neutral weight distribution position for the best overall effect.
You may also sit on the vibration plate, either directly or with a small stool or chair with non-slip feet on the vibration plate for those who cannot stand.  Care must be taken to assure the chair or stool stays centered on the plate.
You can also perform various stretches for increased flexibility.
Or you can use resistance bands or weights while using the VibraSonic and increase the rate of tightening and toning by 30-50%.