Transcript for Runner claims Nike wreaked havoc on her running career
little while but move on to our cover story. Championship runner Mary Cain and she was the fastest girl in America until she joined Nike and she details the training program that left her with broken bones and a broken spirit. Amy is here with that story. Hey, George. That's right. Mary Cain was once R once -- once an olympic openful. This morning track phenom Mary Cain said she was once the fastest girl in America. Makes the move on the outside. Reporter: But her budding career came to a screeching halt when she was encouraged to lose weight and publicly shamed when she didn't. I was weighed in front of teammates. I was told during practices that I was clearly five pounds too heavy. It was public knowledge within the program, within the team that I was really struggling with this. Reporter: The star runner says to "The New York Times," that as part of Nike's Oregon project, coach Alberto Salazar and his assistants emotionally and physically abused her. There's so many people who looked at me at that time and thought that I was living the dream and in certain ways I thought I would be but there was no -- nobody cared about me as a person. I was a product. And I -- I didn't know how to Reporter: Cain became a high school running sensation in bronxville New York and at 17 signed a professional contract training under Salazar where she would win a gold medal at the 2014 world junior champions and two national title. Great moment for Cain. Her personal best. Reporter: But says despite the success, her physical and mental health began to deteriorate as a result of her coach's treatment, she says, in her most desperate moment she even turned to self-harm. I usually cut my legs because I hated them for not running faster for not doing better. And one time the sport site caught me doing it and he just told me to stop. He didn't help me. But I'm really ashamed of that. I knew she was in danger so we called her agent and we told him, you need to get her out of Reporter: She now wonders if they are career would have been different if more women were involved in Nike's program. I think what I regret is at this time I thought to be strong meant going alone, but the truth sur's never alone. There's always people that you can turn to and it's just about finding the right support system. Reporter: When asked for a comment a Nike spokesperson telling ABC news these are deeply troubling allegations which have not been raised by Mary or her parents before. Adding, we take the allegations extremely seriously and will launch an immediate investigation to hear from the Oregon project athletes. At Nike we seek to always put the athlete at the center of everything we do, and these allegations are completely inconsistent with our values. Cain says she wants to change the system and start a new chapter in part by seeing more women in power. Her mother told us that I have sin she was a little girl Cain was determined and focused and once she puts her mind to something there's to stopping her, guys.
This transcript has been automatically generated and may not be 100% accurate.