Katherine Prumm
Auckland-based Prumm, 20, suffered several broken vertebrae in the incident on Saturday but the extent of the injury was unclear.
A brief update on her website said Prumm had "over-jumped a triple step-down" and in the ensuing fall damaged thoracic vertebrae in the middle of her spine.
Prumm was training in preparation for a tilt at the 2009 world title as well as looming events in Australasia and was "naturally shell-shocked" with the injury setback.
The Yamaha rider has endured an horrific year, with her chase for a third world crown ending when she broke her collar bone while training in Germany in June.
Prior to that her campaign was hampered by a pre-season knee injury.
