Simpson, a Monument resident and University of Colorado graduate, finished last in her heat in the 1,500 semifinals. Her Olympics is over.
"I'm not sick. I'm not hurt. I'm not out of shape," Simpson said, breaking into tears. "I just had a shameful performance today, and I'm really sorry to all the people that care about me and work so hard with me."
The other two Americans in the race, Shannon Rowbury and Morgan Uceny, advanced.
"I have no excuse," Simpson said. "I'm in really good shape. The workouts indicate I'm in good shape. I'm ready to run. The one thing I could say, if I could give any tidbit to people following in my footsteps, it's that don't let anyone talk to you about the final until you're in the final. It's so hard when you're a (world) medalist moving into the next year, especially when you have nothing like a crutch, like an injury or something to be like, 'If it doesn't go right, I can blame it on this.'
"I have nothing. I'm in great shape and I feel good. You just have to earn every single step, and I think I thought about the final before I had earned it."
In Monday's first round, Simpson tried to run from the back to avoid elbowing and jostling in the middle of the pack, and it nearly cost her.
When she reached for her kick, it wasn't there.
"Two days ago, I just kind of felt, 'Well, I scared everyone, I cut it too close,' and I just tried to run really hard the whole way today," Simpson said. "It's just tough, because that takes the kick out of your legs. All that said, it shouldn't have (happened). I'm in good enough shape. I should have been able to kick today."
At the world championships a year ago in Daegu, South Korea, Simpson lived a dream. Wednesday was a nightmare.
"I'm in better shape I think than I was last year at this time," Simpson said. "I have no excuse, I didn't execute, and I think maybe part of it was I tried too hard."