"This is an MRI of my hamstring, The white stuff surrounding the muscle is known in the medical world as anti-awesomeness," Foster wrote.
Foster later tweeted that he would be "fine."
Foster was rankled by an ESPN report in which a medical analyst who viewed the image of the MRI predicted he could miss a month.
"If I had a 'significant injury' why post it? I'll be fine, it was jus meant to make fun of the whole situation," he wrote. "Humor is lost nowadays."
"4 those sincerely concerned, I'm doing OK & plan to B back by opening day," he wrote on Twitter. "4 those worried abt your fantasy team, u ppl are sick."
Foster, the 2010 NFL rushing leader, attempted to clarify his original message after Monday's practice, in which he jogged with his Texans teammates. The Houston Chronicle reported
"That's a part of the game," Foster said, referring to fantasy football. "My tweet -- the fact that we're talking about Twitter is amazing to me –- but my tweet got taken out of context. What I was saying that people who value a digital game over a human being's health is just kind of weird to me. And that's all that I meant by that, and people took it as, oh, I don't care about fantasy football. I think it's good for the game. It gets people that don't really watch into it. I'm on my mother's fantasy football team, so I've got to do good.
"It got taken out of context. I love all my fans, and if you've been following me on Twitter, you know what kind of person and human being I am, and if you know me, you know what kind of human being I am. I try to promote peace, man, because that's what I'm all about."