The Chadar trek consists entirely of walking on multitudes of icy surfaces and the frozen Zanskar river. It is extremely important to stay cautious and hence novice trekkers shouldn't opt for the Chadar trek.
It is a high-altitude trek and hence acclimatization is crucial.
A medical check-up is done before one embarks on the Chadar Trek and if a trekker is deemed unfit for the trekker, then they're not allowed to go on the trek no matter what.