The 28-year-old German abandoned the Vuelta a España after four stages citing bronchitis and, although he was back on the bike for the Brussels Cycling Classic and GP de Fourmies, he pulled out of the Tour of Denmark as well, still suffering from similar issues.
The German Cycling Federation announced earlier this week that Degenkolb had been ruled out for the Worlds road race, where he had initially been set to lead the German squad, due to "health problems" and "respiratory problems".
According to a Trek-Segafredo press release on Friday, Degenkolb has been hospitalised for 'further examinations' of what may be causing the issues.
"In the last races he did, John suffered from breathing problems and a serious lack of power that prevented him to perform at his level," said team doctor Jens Hinder.
"His condition was not improving enough over the last week, so we decided he had to undergo more profound examinations of his heart and lungs. John is feeling relatively well but has been hospitalized pending the results of these examinations. We will publish an update on his condition as soon as we have more information."
Degenkolb confirmed the news on Twitter, although he noted: "I am fine and will keep you updated."
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