(Yahoo!News) The P90X workout is one of the biggest fitness trends in the past several years, with enthusiastic endorsements across the cultural spectrum, including everyone from singer Pink to 2012 Republican vice presidential nominee Paul Ryan.

But businessman Matt Lombardi says just one day of the program’s strenuous routine sent him into the emergency room with near kidney failure.

“I simply wanted to get back in shape. I could have killed myself in the process,” Lombardi writes on his site, College Spun.

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