Decree affirmed. The self insurer appeals from a decree awarding compensation for disability which the single member and the reviewing board found was due to the acceleration of a preexisting heart disease produced by the physical exertion of the employee while performing duties arising out of and in the course of his employment as a freight car loader. It is settled thait the acceleration of a preexisting heart disease to the point of disablement may be found to have been a personal injury under the workmen’s compensation act. Griffin’s Case, 315 Mass. 71, 74. Whether the employee’s disability was caused by a gradual deterioration of his heart or was accelerated by exertion or strain was a question of fact for the board to decide. Brzozowski’s Case, 328 Mass. 113, 116. There was evidence, which need not be recounted, to support the finding of the board. A finding supported by evidence will be upheld unless vitiated by error of law, Brown’s Case, 334 Mass. 343, 346, and no such error appears. Costs under G. L. c. 152, § 11A, shall be allowed by the single justice.