On a near-perfect summer day in Central Park, the kids can't stop staring.
They stray from the teacher's single-file line to get closer to Sarah Reinertsen as she prepares for a midmorning run, eyeing her left leg with unabashed curiosity.
"It's my robot leg," Reinertsen says with a grin, gesturing at the sleek carbon prosthetic limb fitted into her upper thigh.
Reinertsen, 37, is small, barely 5 feet, with the sinewy physique of a gymnast. But her resume -- first female leg amputee to complete the Ironman competition, record-setting marathoner, "Amazing Race" participant -- is by no means diminutive.
She was born with proximal femoral focal deficiency, a condition that prevented her thigh bone from growing normally. When she was 7 years old, Reinertsen's parents were faced with the choice of amputating her leg or trying to lengthen it with artificial support and often unsuccessful therapy. At the recommendation of doctors, they decided on amputation.
"It was the hardest decision we made, we were so anxious," said her father, Don Reinertsen, 69, of St. James. "Yet, it was a no-brainer."
Sarah Reinertsen remembers some moments from that time -- the last photo her father took of her with two legs, a year of physical therapy in New York City, teasing from kids at school.
And she certainly remembers the day she accompanied her father to a 10-kilometer run in Plainview and met Paddy Rossbach, an amputee runner. After learning Rossbach had a family, a job in the city, and raced frequently, Reinertsen, then 11, reset her goals.
She got outfitted with a special running prosthesis to complement her everyday one and started visiting Rossbach's physical therapist, an ultramarathoner himself, to improve the range of motion in the new prosthetic.
On the Huntington High School track team, she competed against "the purity of the clock" rather than her two-legged peers. She soon tacked another goal to a list that had been mostly academic ambitions: competing in the Paralympics.
"That became my North Star," she said.
At 17, Reinertsen became the youngest member of the 1992 U.S. Paralympic Team and competed in the 100-meter dash in Barcelona. She plans to try again in 2016 if the triathlon is added.
She has a battery of prostheses -- for running, biking, walking . . . and wearing heels.
Schaffer said the new technology, coupled with the physical strength that amputees have from working "twice as hard" allows those like Reinertsen to compete at high levels, sometimes on par with able-bodied athletes.
She has written an autobiography and inspired a Nike prosthetic shoe sole, and was recently named a spokeswoman for the Got Chocolate Milk campaign. Through the Challenged Athletes Foundation, the California-based Reinertsen is hoping to change the conversation around disability and "make it cool."
"There have been so many people in her life who have helped her along way," Don Reinertsen said. "She might be an inspiration, but I think she just wants to give back."
Reinertsen continues to train full speed for races, logging 30-hour weeks for her upcoming races. She returns to New York in August for the U.S. Ironman, consisting of a 2.4-mile swim, 112-mile bike ride and 26.2-mile run. Then, in November, the New York City Marathon.
"I don't plan to stop until my heart does," she said.