The German sprinter has endured a difficult start to the 2019 season, and things don't appear to be improving, with two months to go until the Tour de France.
Kittel, whose last appearance came with 99th place at Scheldeprijs on April 10, had recently added the Tour de Yorkshire to his programme, with the four-day race running from May 2-5 this week. However, after being announced as one of the big-name riders, he decided not to travel to the UK on Wednesday.
The Katusha-Alpecin team would only cite "health issues", explaining that things had not improved since April and stating that "he is not healthy enough to race".
The team nevertheless confirmed that Kittel is still due to ride the Tour of California later this month, as planned.
Kittel underwent health tests towards the end of 2018, in a hugely disappointing first season with Katusha-Alpecin in which he won just two races, having won 14 the year before. He made a bright start to 2018, winning the Trofeo Palma at Challenge Mallorca and finishing second at the Clasica de Almeria.
However, things soon took a turn for the worse. Third was his best stage finish at the UAE Tour, and he abandoned the subsequent Paris-Nice after struggling in the crosswinds. He went to Belgium to ride the sprint-friendly Classics but did not feature in the bunch sprints at Driedaagse Brugge-De Panne or Scheldeprijs. At Scheldeprijs, a race he has won five times, he was dropped and finished more than 4:30 down.
In the wake of that race, debate started to rage over Kittel's lack of form. Katusha-Alpecin director Dirk Demol said it made "no sense" that he was dropped on the flat, while former pro Jurgen Van Den Broeck, commentating for Sporza, voiced rumours that Kittel was "not busy with his profession" and was "drinking too much beer and wine." Those rumours were vehemently denied by Kittel’s agent.
In his own statement on social media, Kittel said: "Always easy to beat a man when he's on the ground. I'm facing a difficult period and I'm thankful for everyone who is supporting me now. To those people making headlines on my cost now: enjoy your minute of fame!”