Steve Suwe, a spokesman for the state Department of Corrections, responded Tuesday to an article in the National Enquirer, The Miami Herald reported. The Enquirer said Simpson had suffered from "stroke-like symptoms" after his incarceration in December 2008.
Suwe said Simpson, a running back for the Buffalo Bills in his glory days, now works in the gym. His duties include sweeping and picking up equipment.
"He's a model inmate. He has a job. He goes to work. He does his job and stays out of trouble," Suwe said.
Simpson's legal troubles began in 1994 when his ex-wife, Nicole, and her friend, Ron Goldman, were stabbed outside her house in Los Angeles. While Simpson was acquitted after a year-long trial, he was later ordered to pay $33 million in civil damages.
In 2007, Simpson was arrested in Las Vegas and convicted of kidnapping an robbing sports memorabilia dealers. He said he was trying to recover property that had been stolen from him.
Simpson, 64, could be paroled in 2017.