Olympic BMX medallist Jelle van Gorkom has been taken off sleep medication, but Dutch cycling officials say it is “impossible to estimate” how long it will take for him to awake from a coma.
Van Gorkom suffered multiple injuries in a training crash on Tuesday.
The Royal Dutch Cycling Union (KNWU) said he appeared to be recovering but there are “concerns about what impact the accident has had on his brain”.
“The doctors cannot make any statements about this at this stage,” it added.
Van Gorkom, 27, suffered broken ribs, a facial fracture, a tear in the skull and damage to the liver, spleen and kidneys in the accident at a BMX track at the national sports centre in eastern Papendal near Arnhem.
The KNWU said Van Gorkom was no longer receiving sleep medication, which “means he must wake up from the coma on his own”.
Van Gorkom won silver medals at the 2015 World Championships and the 2016 Rio Olympics.