Ali Divita, 19, of the Woodside Vaulters club won the gold-level championship at the United States Equestrian Federation/American Vaulting Association National Championships, while teammate Osborn finished second.
"I didn't even think about [winning, beforehand]. I had no expectations for the competitions, which may be why I did so well," said Divita, a resident of Emerald Hills.
Divita also attributed her success to the aid and support of her parents.
"My mom was really a huge factor in this, just because she trains the horses, and ... [my mom and dad's] support behind the whole thing is really important to me," she said.
Vaulting is a sport in which competitors perform elements of gymnastics and dance on top of a cantering horse. Vaulters perform moves such as shoulder stands and splits on the horse and are scored by judges on their form and degree of difficulty, among other criteria.
Divita and Osborn were far from the only Woodside Vaulters recognized at the national championships in Watsonville, California. In fact, five members of the club placed within the top 15 spots.
Shannyn Poer finished in fifth, Megan Lanfri came in eighth, and Katharine Wick placed 11th.
"We totally push each other to the next level," said Divita.
Divita and Osborn also won AVA gold medals with honors in a separate event at the nationals. They both performed compulsory and freestyle routines and received scores of 9.2 out 10 from the judges — the highest scores in the competition.
A compulsory routine involves "seven basic moves that you learn from when you first start vaulting," said Divita, while the freestyle routine allows the vaulter to choose eight moves.
Divita has been vaulting for seven years. After graduating from Saint Francis High School, she is now a student at the University of California, Berkeley.
"Elizabeth and Ali have had an outstanding vaulting season. Their hard work and dedication was evident, as they performed well at every event in which they competed. ... Our club is fortunate to have so much talent and commitment," said Isabelle Bibbler Parker, Woodside Vaulters head coach.