Image 1 of 5 Marianne Vos (Netherlands) finally breaks her five year streak of silver medals as she wins the 2012 Worlds in Valkenburg (Image credit: Tim de Waele/TDWSport.com) Image 2 of 5 Marianne Vos off the top step for the first time in six years (Image credit: Tim de Waele/TDWSport.com) Image 3 of 5 Marianne Vos at the Giro Rosa with event director Giuseppe Rivolta (Image credit: Giro Rosa) Image 4 of 5 Marianne Vos (Rabo-Liv) (Image credit: Bert Geerts/dcp-bertgeerts@xs4all.nl) Image 5 of 5 Marianne Vos (Netherlands) after claiming back-to-back rainbow jerseys in 2013 (Image credit: Tim de Waele/TDWSport.com)

After being out of competition for almost half a year, Marianne Vos has been given permission to resume training with the defence of her Olympic road title a top priority.

The multi-time world champion suffered for a year from hamstring and back injuries, and after a difficult cyclo-cross season where she had to fight to third place behind Pauline Ferrand-Prevot after dominating for six straight years, she aborted her road season and decided to take a full break for three months.

"Extensive medical research has established that there was over-training," Vos said in her blog last week. "The only thing that helps combat this is complete rest. I then, with the doctors, took up to three months to fully rest. Then again I have undergone a series of medical tests and we can see if I have indeed made progress. At this moment I can do little else but wait."

The results from her stress test came in and doctors have cleared Vos to resume training slowly.

"For a professional athlete, it was hard to have to wait and see," Vos said. "I am therefore extremely pleased that things are going better and that my body enough has been restored to very careful rebuild. It will be a nice winter for me."

Unfortunately, because Vos must build slowly back to her previous level, she will not be able to compete in cyclo-cross over the winter. "The Olympic Games in Rio de Janeiro will remain a dream goal," she said. "First I want to be fully fit. That is now the most important thing. I still cannot put a date on my comeback.

"This is unfortunate and difficult, but I want to not force anything."

Vos will see how she reacts to the training and then decide how quickly she can progress.