"On Saturday I created a rift in the CrossFit community and unintentionally hurt many of its members," Greg Glassman, who started the fitness company, said in a statement announcing his retirement.
Glassman responded to a tweet Saturday by the Institute for Health Metrics and Evaluation, that called racism and discrimination "critical public health issues that demand an urgent response."
Glassman responded: "It's FLOYD-19."
"Your failed model quarantined us and now you're going to model a solution to racism?" he tweeted in a follow-up. "George Floyd's brutal murder sparked riots nationally. Quarantine alone is 'accompanied in every age and under all political regimes by an undercurrent of suspicion, distrust, and riots.' Thanks!"
Reebok, a major sponsor, and affiliated gyms dropped their partnerships with CrossFit after the tweets.
Gyms across the United States, as well as places like malls and theaters, were ordered closed amid the coronavirus epidemic and public health warnings being in close quarters can spread the disease.
Floyd, who is black, died May 25 after a white Minneapolis police officer kneeled on his neck for several minutes as Floyd said he could not breathe. That officer and three others have been fired and criminally charged.
Floyd's death and video of the deadly encounter have sparked protests and calls for police reform across the U.S.
CrossFit on Sunday evening tweeted what it said was a statement from its CEO that read: "I, CrossFit HQ, and the CrossFit community will not stand for racism. I made a mistake by the words I chose yesterday."
"My heart is deeply saddened by the pain it has caused. It was a mistake, not racist but a mistake," the tweet read.
"I was trying to stick it to the @IHME_UW for their invalidated models resulting in needless, economy-wrecking, life-wrecking lockdown, and when I saw they were announcing modeling a solution to our racial crisis, I was incredulous, angry, and overly emotional. Involving George Floyd's name in that effort was wrong," another tweet read.
CrossFit Headquarters also apologized in a letter Tuesday for failing to publicly address issues raised by Floyd's death.
"We pride ourselves on authenticity and truth, but we got it wrong by failing to tell you we really care about black people and support the need for real change," the company said in that statement.
"We weren't sure how to get the message right, and as a result, we failed catastrophically by not effectively communicating care for the Black community, all as the online world was watching and experiencing extreme pain," CrossFit Headquarters said, adding it "failed to meet a moment when the community wanted to hear from us most."
BuzzFeed News reported earlier Tuesday that hours before Glassman sent out the tweets about Floyd and the pandemic Saturday, Glassman made comments to gym owners in a private Zoom call in which he seemed to push back on the expectation that he should mourn Floyd's death or that the brand should issue a statement about it.
CrossFit advertises itself as a lifestyle combining exercise and nutrition and says it has more than 15,000 affiliates around the world. CrossFit said in Tuesday's statement that Dave Castro will take over as CEO.