In any proceeding for the enforcement of a claim for compensation under this chapter it shall be presumed, in the absence of substantial evidence to the contrary:
(1) That the claim is for a covered work injury;
(2) That sufficient notice of such injury has been given;
(3) That the injury was not caused by the intoxication of the injured employee; and
(4) That the injury was not caused by the wilful intention of the injured employee to injure oneself or another.