Fitness brands including Reebok have cut ties with CrossFit after the company's CEO posted a tweet making light of George Floyd's death.
In reply to a public health body saying racism was a public health issue, Greg Glassman tweeted: "FLOYD-19."
He also called an affiliate "delusional" for questioning why CrossFit had been silent on the killing of Floyd by police in Minneapolis.
Mr Glassman has now apologised, saying CrossFit "will not stand for racism".
He said he had been trying to make a point about lockdowns that have been put in place to try to contain the spread of the coronavirus.
CrossFit is a company based on a fitness regimen developed by Mr Glassman, and is incorporated into gyms across the world.
These gyms are run on an affiliate model, paying the main CrossFit company for permission to use the name and regimen.
What did Greg Glassman say?
It began when the Institute for Health Metrics and Evaluation at the University of Washington tweeted that "racism is a public health issue".
In response, Mr Glassman tweeted "FLOYD-19" - a play on Covid-19, the name of the disease caused by the coronavirus.
Mr Glassman also came under fire for an email he reportedly sent to an affiliate who asked for a response from the company on anti-racist protests across the US.
"I sincerely believe the quarantine has adversely impacted your mental health," he reportedly wrote to the woman, before calling her "delusional". "You think you're more virtuous than we are. It's disgusting."
What has the response been?
Since Mr Glassman's tweet about George Floyd, hundreds of affiliate gyms have removed CrossFit from their branding. A spreadsheet tracking all of the gyms that are rebranding currently lists 227 fitness centres distancing themselves from CrossFit.
One of these gyms, Petworth Fitness in Washington DC - formerly CrossFit Petworth - wrote on Instagram: "For a brand that has preached about being 'for all', the deafening silence on current and past issues of racism tells us all we need to know."
It added that it would donate its annual affiliate fee - $3,000 (£2,364) - to the Black Lives Matter DC and Know Your Rights anti-racist campaign groups.
Adidas AG, which owns Reebok, also issued a statement confirming it was ending its relationship with CrossFit.
"Recently, we have been in discussions regarding a new agreement, however, in light of recent events, we have made the decision to end our partnership with CrossFit HQ," the company said in a statement to AFP news agency.
Several CrossFit athletes also criticised the company.
Four-time CrossFit Games champion Matthew Fraser praised a colleague for disaffiliating from the company, while Olympian and three-time CrossFit Games champion Tia-Clair Toomey said she was "incredibly saddened, disappointed and frustrated" with Mr Glassman's comments.
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I wanted to start by saying that I am incredibly saddened, disappointed and frustrated with the actions and words of Crossfit HQ and in particular Greg Glassman. I’m deeply apologetic from the bottom of my heart to all the people who have had to witness this ignorance and the pain it causes. A lack of acknowledgement and empathy for those who are fighting for basic human rights and equality is simply inexcusable and it’s behaviour that we cannot stand for. It has made both Shane and I incredibly ashamed to be a part of an organisation that we have dedicated so much of ourselves to. If it has us angered and disappointed like we are, we couldn’t even begin to imagine how these words and actions affect the extremely diverse global community of crossfitters and supporters who have all dedicated so much time, money and passion to the sport. But this is much bigger than the sport. For those who continue to be dismissive of inequality, you must understand that this is a truly GLOBAL issue and we NO longer can sit idle and do or say nothing. It’s on ALL of us to keep fighting the cause globally until systemic racism and the inhumane treatment of black communities around the globe no longer exists. I said earlier that this issue is much bigger than sport, yet sport and the functional fitness space has a really important part to play. Sport and fitness bring us together and unite us in such a powerful and profound way. I want my platform to drive positivity, unity and the overall message that no matter your skin colour or cultural background, we should all inspire one another to be the best versions of themselves. I want my platform to reflect the values and beliefs of the community I feel most comfortable in, a community that raises up those around them and gives everybody their own individual opportunity to be a champion. My future with Crossfit is unclear and depends on the direction of HQ. I will continue to stand against ignorance and stand alongside those who fight abuse, hatred and racism.
Icelandic CrossFit athlete Katrin Tanja Davidsdottir also posted screenshots of Mr Glassman's tweet and email, and said she was "ashamed, disappointed and angry".
Has CrossFit addressed the backlash?
In a statement posted on CrossFit's Twitter account, Mr Glassman apologised for the tweet and said he was trying to make a point about lockdowns to contain the spread of the coronavirus, which he doesn't agree with.
"I, CrossFit HQ, and the CrossFit community will not stand for racism. I made a mistake by the words I chose yesterday," he said. "My heart is deeply saddened by the pain it has caused. It was a mistake, not racist but a mistake.
"Floyd is a hero in the black community and not just a victim. I should have been sensitive to that and wasn't. I apologise for that.
"I was trying to stick it to the @IHME_UW [Institute for Health Metrics and Evaluation] for their invalidated models resulting in needless, economy-wrecking, life-wrecking lockdown, and when I saw they were announcing modelling a solution to our racial crisis, I was incredulous, angry, and overly emotional. Involving George Floyd's name in that effort was wrong."