Chris Froome warned of the long-term effects of COVID-19, claiming that many riders suffer for months after infection, highlighting the potential risk to the heart.

The Israeli Premier Tech rider first contracted COVID-19 at this year's Tour de France, forcing him to leave the race after 17 stages and curbing what appeared to be significant progress in his long-term recovery from the crash in 2019.

The four-time yellow jersey winner returned for the Vuelta a España, but despite completing 21 stages, he mostly struggled, finishing in the top 100 only five times.

"I wasn't in great shape at the end of the season," Froome said in his latest YouTube video.

"I think I really needed the rest, COVID knocked me around six times."

"I couldn't come back from that. I didn't feel like I had energy on the bike. In the Vuelta I rode to make up the race, but it was flat, flat, flat all the way."

Froome also claimed that "VO2max was definitely affected by COVID."

Froom went to Israel for physiological testing at the beginning of the off-season and recorded a VO2max of 72.1; in 2015, when he was tested to dispel the allegations surrounding his performance, he scored an 84.6 (normalized to 88.2).

Froom emphasized the blow to the cardiovascular system from COVID-19, which he felt extended to other "strange" heart problems. Pericarditis was noted as a possible post-COVID-19 heart problem, which kept Tim DeKlerk, Lizzie Banks, Maggie Rochette, and others from the race.

"There is no doubt that developing COVID can have a significant impact on the heart. It's not just a flu, as many people think, especially for professional riders," said Froome.

"From what I have talked to within the peloton, many riders are suffering from the aftereffects two to three months later.

"It was good to be able to go to Israel and do a whole series of physiological tests and check the VO2 max, which was definitely affected by the COVID. It was also important to check my heart."

Froome, who has been visiting Singapore, Japan, the UAE, and Miami in recent weeks, recently returned to training in Monaco and will attend Israel Premier Tech's pre-season training camp in Spain this week. He has hinted at a possible start in the 2023 Tour Down Under, but his race schedule is still up in the air as Israel Premier Tech prepares to drop out of the World Tour.

"It's great to be back to normal training," Froome said. "My body feels so much better and everything is starting to work better. I don't know if it's the endorphins or what, but it feels great to be back in training."