Final answer:
The risk during exercise testing in a mixed subject population is expressed as the number of events per 10,000 tests.
Step-by-step explanation:
In this case, the risk during exercise testing in a mixed subject population was expressed as the number of events per 10,000 tests. For example, if there were 5 events during exercise testing in a population of 20,000 subjects, the risk would be calculated as 5 events per 10,000 tests.